Method and apparatus for monitoring plasma processing operations

ABSTRACT

The invention generally relates to various aspects of a plasma process, and more specifically the monitoring of such plasma processes. One aspect relates in at least some manner to calibrating or initializing a plasma monitoring assembly. This type of calibration may be used to address wavelength shifts, intensity shifts, or both associated with optical emissions data obtained on a plasma process. A calibration light may be directed at a window through which optical emissions data is being obtained to determine the effect, if any, that the inner surface of the window is having on the optical emissions data being obtained therethrough, the operation of the optical emissions data gathering device, or both. Another aspect relates in at least some manner to various types of evaluations which may be undertaken of a plasma process which was run, and more typically one which is currently being run, within the processing chamber. Plasma health evaluations and process identification through optical emissions analysis are included in this aspect. Yet another aspect associated with the present invention relates in at least some manner to the endpoint of a plasma process (e.g., plasma recipe, plasma clean, conditioning wafer operation) or discrete/discernible portion thereof (e.g., a plasma step of a multiple step plasma recipe). A final aspect associated with the present invention relates to how one or more of the above-noted aspects may be implemented into a semiconductor fabrication facility, such as the distribution of wafers to a wafer production system.

GOVERNMENT RIGHTS

This invention was made with the United States Government support underContract No. DE-AC04-94AL85000 awarded by the U.S. Department of Energy.The Government has certain rights in this invention.

FIELD OF THE INVENTION

The present invention generally relates to the field of plasma processesand, more particularly, to monitoring/evaluating such plasma processes.

BACKGROUND OF THE INVENTION

Plasma is used in various types of industrial-type processes in thesemiconductor and printed wiring board industries, as well as in variousother industries such as in the medical equipment and automotiveindustries. One common use of plasma is for etching away materials in anisolates or controlled environment. Various types of materials may beetched by one or more plasma compositions, including glasses, silicon orother substrate materials, organics such as photoresist, waxes,plastics, rubbers, biological agents, and vegetable matter, and metalssuch as copper, aluminum, titanium, tungsten, and gold. Plasma is alsoutilized for depositing materials such as organics and metals onto anappropriate surface by various techniques, such as via chemical vapordeposition. Sputtering operations may also utilize plasmas to generateions which sputter away material from a source (e.g., metals, organics)and deposit these materials onto a target such as a substrate. Surfacemodification operations also use plasmas, including operations such assurface cleaning, surface activation, surface passivation, surfaceroughening, surface smoothing, micromachining, hardening, andpatterning.

Plasma processing operations can have a significant effect on acompany's profit margin. This is particularly true in the semiconductorand printed wiring board industries. Consider that a singlesemiconductor fabrication facility may have up to 200-300 processingchambers and that each processing chamber in commercial production mayprocess at least about 15-20 wafers per hour. Further consider that aneight inch wafer which is processed in one of these chambers in somecases may be used to produce up to 1,500 semiconductor chips which areeach worth at least about $125, and that each of these semiconductorchips are in effect "pre-sold." Therefore, a single wafer which hasundergone an abnormal plasma process and which is scrapped will resultin lost revenues of at least about $187,500.

The particular plasma process which acts on the wafer such that asemiconductor device may be formed therefrom is commonly referred to asa plasma recipe. Some skilled in the art refer to a plasma recipe asbeing a combination of one or more plasma steps, each of which isexecuted for a fixed period of time. However, "plasma recipe" as used inrelation to the present invention means a plasma processing protocolwhich includes one or more different and distinct plasma steps (e.g., acertain combination of certain steps). "Different and distinct" meansthat each plasma step produces a different, predetermined result on theproduct being processed (e.g., a wafer). Differences between plasmasteps may be realized by changing one or more process conditions,including without limitation the composition of the plasma, thetemperature and pressure in the processing chamber, DC bias, pumpingspeeds, and power settings. The sequence of the plasma steps, as well asthe result of each plasma step, also produces a desired overall orcumulative end result for the plasma recipe.

Plasma processes may be run on wafers in a commercial productionfacility in the following manner. A cassette or boat which stores aplurality of wafers (e.g., 24) is provided to a location which may beaccessed by a wafer handling system associated with one or moreprocessing chambers. One wafer at a time is processed in the chamber,although some chambers may accommodate more than one wafer at a time forsimultaneous plasma processing. One or more qualification wafers may beincluded in each cassette, and the rest are commonly referred to asproduction wafers. Both the qualification and production wafers areexposed to the same plasma process in the chamber. However, nosemi-conductor devices are formed from a qualification wafer asqualification wafers are processed and retained solely fortesting/evaluating the plasma process, whereas semiconductor devices areformed from the production wafers. Further processing operations ofthese now plasma processed production wafers may be required beforesemiconductor devices are actually formed from such production wafers.

Monitoring is employed by many plasma processes to evaluate one or moreaspects of the process. One common monitoring technique associated withplasma recipes run on wafers is endpoint detection. Current endpointdetection systems attempt to identify when a single plasma step of agiven plasma recipe is complete, or more specifically that point in timewhen the predetermined result associated with the plasma step has beenproduced on the product. A representative "predetermined" result is whena layer of a multi-layered wafer has been completely removed in a mannerdefined by a mask or the like. Although prior art systems exist forattempting to identify the endpoint of a single step of a multiple stepplasma recipe, no known system is able to identify the endpoint of eachstep of a multiple step plasma recipe, or even any two steps of amultiple step recipe for that matter.

Having the ability to terminate a given plasma step at its endpoint orjust after endpoint is reached would reduce costs in a number of ways.Obviously, the amount of gases which are used to generate the plasma maybe reduced by terminating a given plasma step when it has achieved itsdesired result. More importantly, terminating a given plasma step at orvery shortly after its endpoint has been reached prevents the wafer frombeing over-etched to an undesired degree. Over-etching a wafer removesmore material from the wafer than desired, such as by etching awayportions of the layer immediately following that which was to be etched,and may also result in the undesirable sputtering of materials ontoother portions of the wafer. The resulting effect on the semiconductordevice(s) formed from this wafer may reduce the quality of thesemiconductor device(s), may go undetected until the semiconductordevice(s) has been delivered to the customer which would not bedesirable if the device(s) was defective or deficient in any way, orboth. Finally, a certain degree of over-etching of a wafer may result inthe wafer simply being scrapped.

Endpoint detection is desirable in theory for plasma processes. Certaindeficiencies became evident as attempts were made to implement endpointdetection techniques in commercial fabrication facilities. Initially,all known endpoint detection techniques were developed by firstchemically analyzing the subject plasma operation to identify awavelength to key in on as being indicative of endpoint. Fabricationfacilities typically run a multiplicity of plasma recipes. As such,these known endpoint detection techniques increase costs due to therequired retention of an experienced chemist. Moreover, these techniquesoften do not produce the intended result - that is the wavelength whichis selected by the chemist may in fact not be at all indicative ofendpoint when the plasma step is actually run since it is only "theory"based. A given endpoint detection technique may also be dependent uponthe processing chamber on which the technique was developed. Accurateresults may not be realized when the endpoint detection technique isused on other processing chambers. Therefore, it would be desirable tohave a plasma monitoring system in which the amount of chemical"pre-analysis" is reduced and which would allow the plasma monitoringsystem to work to an acceptable degree on multiple processing chambers(i.e., a generic plasma monitoring system which was able to identify therelevant endpoint).

Commonly used endpoint detection techniques provide no information onhow the plasma process has actually proceeded or the "health" of theplasma process--only if and when an endpoint of the subject plasma stephas been reached. Other monitoring techniques which are commonly used inplasma processes suffer from this same type of deficiency. Pressures,temperatures, and flow rates of the feed gases used to form the plasmaare commonly monitored. Various aspects relating to the electricalsystem associated with the plasma are also monitored, such as the powersettings being utilized since this will affect the behavior of theplasma. However, these types of monitoring operations do not necessarilyprovide an indication of how the plasma process is actually proceeding.All of the "hardware" settings may be correct, but still the plasma maynot be performing properly for a variety of reasons (e.g., an"unhealthy" plasma). Since errors in a plasma process are typicallydetected by some type of post processing, destructive testing technique,multiple wafers are typically exposed to the faulty plasma processbefore the error is actually identified and remedied. Therefore, itwould be desirable to have a plasma monitoring system which provided amore accurate indication of how the current plasma process was actuallyproceeding on a more "real-time" basis, and thereby allowed for areduction in the number of wafers which are exposed to abnormal plasmaprocesses. Moreover, it would be desirable to have a plasma monitoringsystem which identified the existence of an error in the plasma processat least before the next wafer is exposed to such an "abnormal" plasmaprocess.

Other areas of the semiconductor manufacturing process can adverselyimpact the profit margin of the commercial fabrication facility. Oftenan operator will run the wrong plasma recipe and the resulting waferswill be scrapped. It would be desirable for a plasma monitoring systemto readily identify the plasma recipe being run on the given chamber toavoid this type of situation. Moreover, the length of each step of agiven plasma recipe is typically set for a certain amount of time whichaccounts for the worst case condition (i.e., such that even the"slowest" running of the plasma step will be completed in this timeframe). In many cases the step will actually be completed a significanttime before this maximum setting is reached, causing the problemsidentified in the discussion of endpoint detection. Therefore, it wouldbe desirable to have a plasma monitoring system which was able toidentify the steps of a plasma recipe as it was being run within aprocessing chamber, and to utilize this information in relation to thecontrol of the plasma process (e.g., to terminate the current step,initiate the next plasma step, or both).

Plasma processing of product (e.g., wafers) within the processingchamber will likely have an effect on the interior of the processingchamber which in turn may have an adverse effect on subsequent plasmarecipes which are run on product within the chamber. Certain"byproducts" of a plasma process run on product in the chamber may bedeposited on one or more interior surfaces of the chamber. Thesedeposits may have some type of adverse effect on one or more plasmarecipes which are being run in the processing chamber (e.g., aprocessing chamber may be used to run more than one type of plasmarecipe). Deposits on the interior surfaces of the processing chamber mayhave the following exemplary effects on the performance of the chamber:a longer period of time may be required to reach the endpoint of one ormore plasma steps of the plasma recipe; endpoint of one or more plasmasteps may never be reached; and a result which is different thanexpected of the current plasma step may be undesirably realized (i.e.,an unexpected/undesirable result). Processing chambers are typicallyremoved from the production line on a scheduled, periodic basis for acleaning operation to address the above-noted conditions, regardless ofwhether the chamber is actually in condition for a cleaning and even ifthe chamber was ready for cleaning well before this time. It would bedesirable to have a plasma monitoring system which would provide anindication of when a processing chamber should be removed fromproduction for cleaning.

Cleaning operations which are used to address the above-noted depositsinclude plasma cleans of the interior of the processing chamber, wetcleans of the interior of the processing chamber, and replacement ofcertain components of the processing chamber which may actually beconsumed by the plasma processes conducted therein and are thereforecommonly referred to as "consumables". A plasma clean addresses theabove-noted deposits by running an appropriate plasma in the processingchamber typically without any product therein (e.g., no productionwafers), and therefore with the chamber being in an "empty" condition.The plasma acts on these deposits in a plasma clean and reduces thethickness thereof by chemical action, mechanical action, or both.Resulting vapors and particulate matter are exhausted from the chamberduring the plasma clean. It would be desirable to have a plasmamonitoring system which would provide an accurate indication of both thehealth and endpoint of the plasma clean currently being conducted withinthe processing chamber.

In some cases a plasma clean alone will not adequately address thecondition of the interior of the processing chamber. Another cleaningtechnique which may be employed, alone or in combination with a plasmaclean, is commonly referred to as a "wet clean." Various types ofsolvents or the like may be used in a wet clean and are manually appliedby personnel. In this regard, the subject processing chamber isdepressurized, the chamber is opened to gain appropriate access, and theinterior surfaces of the chamber are manually wiped down such that thesolvents may remove at least some of the deposits by chemical action,mechanical action, or both. It would further be desirable to have aplasma monitoring system which would provide an accurate indication ofwhen further execution of a plasma clean of the interior of theprocessing chamber will be substantially ineffective such that a wetclean may be more timely initiated or eliminated altogether.

Wet cleans and plasma cleans of the interior surfaces of the processingchamber may be ineffective in addressing deposits after a certain numberof plasma processes have been conducted in the chamber. Sufficientdegradation of the interior surfaces of the processing chamber maynecessitate that certain components of the chamber be replaced.Components of the processing chamber which are typically replaced onsome type of periodic basis are the showerhead, the wafer platform, thewafer pedestal, the quartz bell jar, and the quartz bell roof.

Additional processing of the interior surfaces of the chamber istypically undertaken after a wet clean has been performed, after one ormore components of a processing chamber have been replaced and prior toresuming commercial use of the chamber (e.g., the processing of wafersin the chamber for commercial purposes), and in the case of a newchamber for that matter. No product is present in the processing chamberas a plasma is introduced into the now sealed processing chamber in thistype of operation which is also commonly referred to as a plasmacleaning operation. Plasma cleaning operations in this instance addressthe solvent residuals from the wet clean, "prep" the new components ofthe chamber for plasma processing of product in the chamber, or both. Itwould be desirable to have a plasma monitoring system which wouldprovide an accurate indication of both the health and endpoint of theplasma cleaning operation in this type of case.

Conditioning wafers may be run through the processing chamber beforerunning production wafers through the processing chamber after any typeof cleaning of the processing chamber, after any components of thechamber have been replaced, or in the case of a new chamber which hasnever had any plasma processes conducted therein. An entire plasmaprocesses is typically run on one or more conditioning wafers disposedin the subject processing chamber in a conditioning wafer operation.Conditioning wafers may simply be "blanks" or may have somesemiconductor device components thereon, and the running of entireplasma processes thereon may do nothing to the conditioning wafers orportions of the conditioning wafer may be etched. Nonetheless, nosemiconductor devices are ever formed from a conditioning wafer and nointegrated circuit of any kind is ever etched onto a conditioning waferwhile running the plasma recipe thereon. Instead, conditioning wafers ofthis type are either refurbished (e.g., material is redeposited backinto those areas which were etched during the conditioning waferoperation) and re-used again as a conditioning wafer or they arescrapped. The processing of these conditioning wafers further "preps" or"seasons" the chamber and is done for the purpose of placing the chamberin a certain condition for production. No devices are currently beingused to identify when the processing of the conditioning wafers hasachieved its intended purpose. Therefore, it would be desirable to havea plasma monitoring system which would provide an accurate indication ofwhen the conditioning wafer operation may be terminated, as well as thehealth of such an operation.

SUMMARY OF THE INVENTION

The claims in the subject patent application are directed to the firstaspect discussed in the preface to the Detailed Description section ofthe present patent application. The other aspects addressed in the notedpreface are presented in one or more other related patent applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a wafer production system;

FIG. 2 is a perspective view of one embodiment of the wafer cassetteincorporated in the wafer production system of FIG. 1;

FIGS. 3A-B are top and side views, respectively, of one embodiment ofthe wafer handling assembly incorporated in the wafer production systemof FIG. 1;

FIG. 4 is a cross-sectional view of one embodiment of a plasmaprocessing chamber which may be incorporated in the wafer productionsystem of FIG. 1, namely a dry etching chamber;

FIG. 5 is a schematic view of one embodiment of a gas delivery systemfor the processing chamber of FIG. 4;

FIG. 6 is a schematic view of one embodiment of a plasma monitoringassembly which may be incorporated in the wafer production system ofFIG. 1;

FIG. 7 is a flowchart of one embodiment of the plasma monitoring moduleused by the plasma monitoring assembly of FIG. 6;

FIG. 8 is a spectral pattern of one embodiment of a plasma recipe whichmay be run on the system of FIG. 1;

FIG. 9 is a flowchart of one embodiment of a plasma spectra directoryand its various subdirectories which may be used in plasma monitoringoperations;

FIG. 10 is a flowchart of one embodiment of a general data managementstructure which may be utilized for the various subdirectories of theplasma spectra directory of FIG. 9;

FIG. 11 is a flowchart of one embodiment of how data within the generaldata management structure of FIG. 10 may be condensed/consolidated;

FIG. 12A is one embodiment of a data management structure which may beused for the normal spectra subdirectory of FIG. 9;

FIG. 12B is one embodiment of a data management structure which may beused for the abnormal spectra and unknown spectra subdirectories of FIG.9;

FIG. 13 is a flowchart of one embodiment of a pattern recognition modulewhich may be used by the current plasma process module of FIGS. 7 and 32in the evaluation of a plasma process being run in the processingchamber of FIG. 1;

FIG. 14 is a flowchart of one embodiment of a process alert module whichmay be used by the current plasma process module of FIGS. 7 and 32 inthe evaluation of a plasma process being run in the processing chamberof FIG. 1;

FIG. 15 is a flowchart of one embodiment of a startup module to accessthe current plasma process module of FIGS. 7 and 32 for the evaluationof a plasma process being run in the processing chamber of FIG. 1;

FIG. 16 is a flowchart of one embodiment of a startup subroutine whichmay be accessed by the startup module FIG. 15;

FIGS. 17A-C are exemplary spectra of one type of plasma process that maybe run in any of the processing chambers of FIG. 1 and monitored by thecurrent plasma process module, namely a three-step plasma recipe;

FIGS. 18A-C are exemplary spectra of another type of plasma process thatmay be run in any of the processing chambers of FIG. 1 and monitored bythe current plasma process module, namely a plasma cleaning operationwithout first wet cleaning the chamber at the start, at an intermediatetime, and end of such a plasma cleaning operation, respectively;

FIGS. 19A-C are exemplary spectra of another type of plasma process thatmay be run in any of the processing chambers of FIG. 1 and monitored bythe current plasma process module, namely a plasma cleaning operationconducting after a wet clean of the chamber at the start, anintermediate time, and end of such a plasma conditioning operation,respectively;

FIGS. 20A-C are exemplary spectra of another type of plasma process thatmay be run in any of the processing chambers of FIG. 1 and monitored bythe current plasma process module, namely a conditioning wafer operationat the start, an intermediate time, and end of such a conditioning waferoperation, respectively;

FIG. 21 is a flowchart of one embodiment of a plasma health subroutinewhich may be used by the plasma health module of FIGS. 7 and 32;

FIG. 22 is a flowchart of another embodiment of a plasma healthsubroutine which may be used by the plasma health module of FIGS. 7 and32;

FIG. 23 is a flowchart of one embodiment of a plasma health/processrecognition subroutine which may be used by the plasma health module ofFIGS. 7 and 32;

FIG. 24 is a flowchart of another embodiment of a plasma health/processrecognition subroutine which may be used by the plasma health module ofFIGS. 7 and 32;

FIG. 25 is a flowchart of one embodiment of a plasma health/process steprecognition subroutine which may be used by the plasma health module ofFIGS. 7 and 32;

FIGS. 26A-C are exemplary spectra from a "clean" processing chamber,from an "aging" processing chamber, and from a "dirty" processingchamber, respectively;

FIG. 27 is a flowchart of one embodiment of a chamber conditionsubroutine which may be incorporated in the chamber condition module ofFIGS. 7 and 32;

FIG. 28 is a flowchart of another embodiment of a chamber conditionsubroutine which may be incorporated in the chamber condition module ofFIGS. 7 and 32;

FIG. 29 is a flowchart of another embodiment of a chamber conditionsubroutine which may be incorporated in the chamber condition module ofFIGS. 7 and 32;

FIGS. 30A-D are exemplary spectra from the processing chamber in a"dirty chamber" condition, at the end of a wet clean, at the end of aplasma clean, and at the end of a conditioning wafer operation,respectively;

FIG. 31 is a schematic view of another embodiment of a plasma monitoringassembly which may be incorporated in the wafer production system ofFIG. 1, which includes the current plasma process module from FIG. 7above, and which also includes a calibration module;

FIG. 32 is a flowchart of one embodiment of a plasma monitoring modulewhich may be used by the plasma monitoring assembly of FIG. 31, as wellas by the plasma monitoring assembly of FIG. 37 below;

FIG. 33 is a schematic view of one embodiment of the spectrometerassembly of FIG. 31;

FIG. 34 is one embodiment of the fiber optic cable assembly whichoperatively interfaces the window and plasma monitoring assembly in FIG.31;

FIG. 35 is a schematic view of the axes of the calibration light sentand reflected by the inner and outer surfaces of the window of FIG. 31;

FIG. 36 is one embodiment a fixture assembly for interconnecting thefiber optic cable assembly of Figure,34 with the window on theprocessing chamber presented in FIG. 31;

FIG. 37 is a schematic view of another embodiment of a plasma monitoringassembly which may be incorporated in the wafer production system ofFIG. 1, which includes the current plasma process module from FIG. 7above, and which also includes a calibration module;

FIG. 38 is a schematic view of the axes of the calibration light sentand reflected by the inner and outer surfaces of the window of FIG. 37;

FIG. 39 is one embodiment a fixture assembly for interconnecting thefiber optic cables with the window on the processing chamber in theconfiguration presented in FIG. 37;

FIG. 40 is a flowchart of one embodiment of the calibration module fromFIG. 32;

FIG. 41 is a flowchart of one embodiment of a calibration subroutinewhich may be used by the calibration module of FIG. 40;

FIG. 42 is one embodiment of a spectra of a calibration light which maybe used by the calibration module of FIG. 40;

FIG. 43 is one embodiment of a spectra of that portion of thecalibration light of FIG. 42 which is reflected by the inner surface ofthe processing chamber window when there are at least substantially nodeposits formed thereon;

FIG. 44 is a cutaway view of another embodiment of a spectrometer whichmay be used by the spectrometer assembly of FIG. 31 and which isoperatively interfaced with the calibration module of FIG. 40;

FIG. 45 is a flowchart of another embodiment of a calibration subroutinewhich may be used by the calibration module of FIG. 40;

FIG. 46A is one embodiment of a spectra of a calibration light which maybe used by the calibration module of FIG. 40 to identify an intensityshift condition;

FIG. 46B is another embodiment of a spectra of a calibration light whichmay be used by the calibration module of FIG. 40 to identify anintensity shift condition;

FIG. 47A is one embodiment of a spectra of that portion of thecalibration light of FIG. 46A which is reflected by the inner surface ofthe processing chamber window when in a degraded or aged condition;

FIG. 47B is one embodiment of a spectra of that portion of thecalibration light of FIG. 46B which is reflected by the inner surface ofthe processing chamber window when in a degraded or aged condition;

FIG. 48 is a flowchart of another embodiment of a calibration subroutinewhich may be used by the calibration module of FIG. 40;

FIG. 49 is a flowchart of one embodiment of a research subroutine whichmay be used by the research module of FIGS. 7 and 32;

FIGS. 50A-C are exemplary plots of intensity versus time for 3wavelengths generated by the research subroutine of FIG. 49 from onerunning of a plasma recipe on product in one of the chambers from FIG.1;

FIGS. 51A-C are exemplary plots of intensity versus time for same 3wavelengths presented in FIGS. 50A-C, but from another running of thesame plasma recipe on product in the same processing chamber;

FIG. 52 is a flowchart of one embodiment of an endpoint detectionsubroutine which may be used by the endpoint detection module of FIGS. 7and 32;

FIG. 53 is a flowchart of another embodiment of an endpoint detectionsubroutine which may be used by the endpoint detection module of FIGS. 7and 32;

FIG. 54A is an exemplary spectra from a processing chamber at the startof a plasma process step;

FIG. 54B is an exemplary spectra which has been selected as beingindicative of endpoint of the plasma process step from FIG. 54A for useas a reference by the endpoint detection subroutine of FIG. 53;

FIG. 54C is the difference between the spectra of FIGS. 54A and 54B inaccordance with the endpoint detection subroutine of FIG. 53;

FIG. 55A is an exemplary spectra from a processing chamber at anintermediate time of the plasma process step presented in FIG. 54A;

FIG. 55B is the same spectra from FIG. 54B;

FIG. 55C is the difference between the spectra of FIGS. 55A and 55B inaccordance with the endpoint detection subroutine of FIG. 53;

FIG. 56A is an exemplary spectra from a processing chamber at theendpoint of the plasma process step presented in FIG. 54A;

FIG. 56B is the same spectra from FIG. 54B;

FIG. 56C is the difference between the spectra of FIGS. 55A and 55B inaccordance with the endpoint detection subroutine of FIG. 53;

FIG. 57 is a flowchart of another embodiment of an endpoint detectionsubroutine which may be used by the endpoint detection module of FIGS. 7and 32;

FIG. 58 is an exemplary optical emissions output which would beindicative of the endpoint of a plasma process step in accordance withthe endpoint detection subroutine of FIG. 57;

FIG. 59 is a flowchart of one embodiment of a wafer distributionsubroutine which may be incorporated in the wafer distribution module ofFIGS. 7 and 32; and

FIG. 60 is a flowchart of another embodiment of a wafer distributionsubroutine which may be incorporated in the wafer distribution module ofFIGS. 7 and 19.

DETAILED DESCRIPTION Preface

The present invention generally relates to various aspects of a plasmaprocess. These aspects may be grouped into four main categories. Onecategory relates in at least some manner to a calibration orinitialization procedure, associated components, or both. The firstaspect through the fourth aspect presented below are within thiscategory. Another category relates in at least some manner to varioustypes of evaluations which may be undertaken of a plasma process whichwas run, and more typically one which is currently being run, within theprocessing chamber (e.g., plasma health evaluations, plasmaprocess/plasma process step identification, plasma "on" determinations).The fifth aspect through the eighth aspect presented below are withinthis second category. Yet another category associated with the presentinvention relates in at least some manner to the endpoint of a plasmaprocess (e.g., plasma clean, conditioning wafer operation) ordiscrete/discernible portion thereof (e.g., a plasma step of a multiplestep plasma recipe). The ninth aspect through the thirteenth aspectpresented below are within this third category. Finally, the fourthcategory associated with the present invention relates to how one ormore of the above-noted aspects may be implemented into a semiconductorfabrication facility. The fourteenth aspect through the seventeenthaspect presented below are within this fourth category.

A first aspect of the present invention is embodied in a plasmaprocessing system having calibration capabilities in relation to themonitoring of plasma processing operations. The plasma processing systemincludes a processing chamber having a window with an inner surfacewhich is exposed to plasma processes conducted within the chamber and anouter surface which is isolated from such processes. A plasma generatoris associated with the plasma processing system to provide the plasmafor the plasma processes. Any technique and corresponding structure forforming a plasma in the chamber is appropriate for this first aspect ofthe present invention. A first spectrometer assembly (e.g., one or morespectrometers of any type, such as scanning-type spectrometers and solidstate spectrometers) is located outside of the chamber and isoperatively interconnected with the window through a first fiber opticcable assembly (e.g., one or more fiber optic cables). A calibrationlight source is also located outside of the chamber and operativelyinterconnected with the window through a second fiber optic cableassembly (e.g., one or more fiber optic cables). Ends of the first andsecond fiber optic cable assemblies may be disposed on, but arepreferably spaced from, the outer surface of the window to establish thenoted operative interconnection in the nature of receiving datatransmitted through the window.

In one embodiment of the first aspect of the present invention,"calibration" involves a comparison between data relating to thecalibration light which is sent to the window by the calibration lightsource (e.g., a pattern, intensity, or both, of the correspondingoptical emissions) and data relating to a first portion of this samecalibration light which is reflected by the inner surface of the windowon the processing chamber (e.g., a pattern, intensity, or both, of thefirst portion). The inner surface of the window of the processingchamber is that portion of the window which is typically affected byplasma processes conducted within the chamber. Changes on the innersurface of the window may have an effect on any evaluation of a plasmaprocess being conducted within the chamber if such an evaluation isbased upon the transmission of optical emissions through the window.These changes may be identified through the use of the noted calibrationlight since changes to the inner surface of the window will affect thereflection of the calibration light by the inner surface. Therefore, the"calibration" available from this embodiment of the first aspect of theinvention may be used to calibrate an "optical emissions based" plasmamonitoring system by making at least one adjustment in relation to sucha system based upon the above-noted comparison. The types of"adjustments" which are contemplated by this embodiment of the firstaspect are addressed in relation to the third aspect of the inventionpresented below.

Information on the window in relation to calibration in accordance withthe first aspect of the present invention preferably includesinformation which is specific to the inner surface of the window on theprocessing chamber through which optical emissions are obtained. Thatis, calibrations in accordance with this first aspect are preferably inrelation to only the inner surface of the window and not the outersurface of the window. Steps may be undertaken such that the portion ofthe calibration light which is reflected by the inner surface of thewindow is readily available for comparison with the calibration light inthe form as it is being sent to the window in another embodiment of thesubject first aspect. This may be accomplished through appropriatelyconfiguring the window. For instance, at least a portion of the window,which includes that area where the calibration light impacts the window,may have a generally wedge-shaped configuration (e.g., variable windowthickness). Another characterization of a window configuration in thisembodiment is that at least a portion of the inner and outer surfaces ofthe window may be disposed in non-parallel relation. These types ofconfigurations are particularly useful when the relevant ends of thefirst and second fiber optic cable assemblies are coaxially disposed orare at least disposed in parallel relation. In this regard, the ends ofthe first and second fiber optic cable assemblies may be disposed suchthat reference axes extending from the ends of these fiber optic cableassemblies will each impact the outer surface of the window at an angleother than perpendicular, but will each impact the inner surface of thewindow in at least substantially perpendicular fashion. As such, thatportion of the calibration light which is reflected by the outer surfaceof the window will be directed away from the end of the first opticcable assembly and will not be "collected" thereby. However, at leastpart of that portion of the calibration light which is reflected by theinner surface of the window will be directed back to the end of thefirst fiber optic cable assembly such that it is available to the firstspectrometer assembly and thereby available for the above-notedcomparison.

Another way to collect that portion of the calibration light which isreflected by the inner surface of the window instead of that which isreflected by the outer surface of the window may be done with aconventional window or where the inner and outer surfaces of the windoware at least substantially parallel (e.g., a uniform thickness windowconfiguration). In this case, the ends of the first and second fiberoptic cable assemblies may be laterally displaced and directed to thesame general area on the window from at least generally equal but"opposite" acute angles (e.g., "pointing" toward the same general areaat an angle other than perpendicular, but from generally an "opposite"direction). To illustrate this characterization, consider a referenceplane which extends through the inner and outer surfaces of the windowsubstantially perpendicularly thereto. The end of the second fiber opticcable assembly would be disposed on a first side of this referenceplane, displaced therefrom, and directed toward the window and at leastgenerally in the direction of the reference plane such that lightleaving its end would impact the outer surface of the window at an angleother than perpendicular. The end of the first fiber optic cableassembly would be disposed on a second side of this same reference plane(opposite the first side), displaced therefrom, and directed toward thewindow and at least generally in the direction of the reference planesuch that at least a portion of the calibration light which is reflectedby the inner surface of the window would be "collected" by the firstfiber optic cable assembly for provision to the first spectrometerassembly. The thickness of the window will define at least in part theamount by which that portion of the calibration light which is reflectedby the inner surface of the window is offset from that portion of thecalibration light which is reflected by the outer surface of the window,and thereby the "sensitivity" to the relative positionings between theends of the first and second fiber optic cable assemblies to collectonly light reflected by the inner surface of the window versus its outersurface.

Anti-reflective coatings may also be applied to the outer surface of thewindow to reduce the effects of that portion of the calibration lightwhich is reflected by the outer surface of the window--that is such thata comparison may be made between the calibration light that is sent tothe window with that portion of the calibration light which is reflectedby the inner surface of the window. A window with parallel inner andouter surfaces could be used with an arrangement whereby the ends of thefirst and second fiber optic cable assemblies were coaxially disposedand oriented such that reference axes projecting from their respectiveends impacted both the inner and outer surfaces in at leastsubstantially perpendicular fashion. Application of an anti-reflectivecoating to the outer surface of the window would reduce the amount oflight which is reflected from the outer surface of the window anddirected back to the first fiber optic cable assembly for provision tothe first spectrometer assembly in this instance. However, there wouldstill be some reflection from the outer surface which would be providedto the first spectrometer assembly along with the desired reflectionfrom the inner surface. Therefore, preferably such an anti-reflectivecoating is used in combination with the above-noted techniques whichprovide for some degree of separation of the calibration light reflectedfrom the inner and outer surfaces of the window.

Another embodiment of the first aspect of the present invention relatesto a fiber optic cable fixture assembly. One application of this fixtureassembly is to maintain one or more of the relevant ends of the firstand second fiber optic cable assemblies in a fixed positionalrelationship relative to the window. Another application of this fixtureassembly is to detachably interconnect one or more of, and morepreferably each of, the first fiber optic cable assembly, the secondfiber optic cable assembly, and the window with the processing chamber(e.g., with one or more threaded fasteners). One embodiment of such afixture assembly is particularly useful for the case where at least theends of the first and second fiber optic cable assemblies are coaxialand where the window is configured to provide for separation of thatportion of the calibration light which is reflected by the inner surfaceof the window from that portion of the calibration light which isreflected by the outer surface of the window (e.g., using a generallywedge-shaped configuration for the window). In this case, the fixtureassembly would include a recessed region which interfaces with orprojects toward at least a portion of the outer surface of the window.At least a portion of the surface of the fixture assembly which definesthis recessed region would include a light absorbing material to accountfor that portion of the calibration light reflected by the outer surfaceof the window (i.e., to absorb light which is reflected by the outersurface if it impacts the body of the fixture assembly). A first portwould extend through the fixture assembly and intersect the recessedregion in an orientation such that a reference axis projecting from theends of the first and second fiber optic cable assemblies each wouldintersect the outer surface of the window at an angle other thanperpendicular, and further such that each would intersect the innersurface of the window at least at a substantially perpendicular angle.Therefore, this embodiment of the fixture assembly may be used to retainthe window and first and second fiber optic cable assemblies in a fixedrelative positional relationship which allows the first fiber opticcable assembly to collect only that portion of the calibration lightwhich is reflected by the inner surface of the window not from the outersurface of the window.

Another embodiment of the first aspect of the present invention relatesto the use of at least two different types of light by the calibrationlight source. One of these calibration lights may include a plurality ofdiscrete intensity peaks, while the other of these lights may be definedby a continuum of intensity or where there are no discernible peaks(e.g., a constant intensity, a continually changing intensity, or acombination of both). In addition, one of these calibration lights maybe used to identify one type of condition requiring calibration (e.g., awavelength shift associated with the optical emissions data obtainedthrough the window) while the other may be used for another, differenttype of condition requiring calibration (e.g., an intensity shiftassociated with the optical emissions data obtained through the window,a complete filtering of some part of the optical emissions transmittedthrough the window). How these types of light sources may be used toidentify these types of conditions is addressed below in relation to thesecond aspect. Any one or more of the features discussed below on thesecond aspect therefore may be utilized in combination with the variousfeatures addressed in this embodiment of the first aspect of the presentinvention as well.

A second aspect of the present invention relates to one or more"conditions" which may be identified during some type of a calibrationof a plasma processing system. Each of the various embodiments of thissecond aspect are embodied in a plasma processing system which includesa processing chamber, some type of a plasma monitoring assembly whichmonitors/evaluates (in at least some manner) plasma-based processesconducted within the chamber through optical emissions data of theplasma in the chamber during the process, and a calibration assemblywhich is operatively interfaced with this plasma monitoring assembly.

One embodiment of the calibration assembly associated with the secondaspect of the present invention calibrates the plasma monitoringassembly for one or more conditions. One of these conditions is awavelength shift which may be experienced in relation to the opticalemissions data obtained on the subject plasma process. Another of theseconditions is an intensity shift which may be experienced in relation tothe optical emissions data obtained on the subject plasma process. Yetanother of these conditions is where certain of the optical emissions,which should be available on the subject plasma process, are being atleast substantially completely filtered (e.g., blocked out) by thewindow. Finally, one of these conditions is where the window is havingdifferent effects on different portions of the optical emissions. Thiswould be the case where there are differing intensity shifts or multipledampening effects throughout the optical emissions data being obtainedon the subject plasma process. Any combination of the foregoingconditions may be identified and calibrated for by the calibrationassembly of the second aspect of the present invention.

The calibration assembly discussed above in relation to the first aspectof the present invention may be used to identify and calibrate thesubject plasma monitoring assembly for any of the above-noted types ofconditions in relation to the second aspect of the present invention.Wavelength shifts may be identified through using a calibration lighthaving a plurality of discrete and displaced (at different wavelengths)intensity peaks. Any shifting in the wavelengths at which these peaksappear in the calibration light which is sent to the window (calibrationlight) in relation to that portion of the calibration light which isreflected by the inner surface of the window (reflected light) would beindicative of a wavelength shift and which could be addressed and morepreferably at least substantially alleviated by calibration. Intensityshifts may also be identified with this type of light by noting how theintensity of the peaks vary between the calibration light and thereflected light. Some peaks in the reflected light may be dampened inrelation to the calibration light more than others, which would indicatethe existence of multiple dampening effects. Peaks which were present inthe calibration light but which were absent in the reflected light wouldindicate that there is filtering at those wavelengths where the peaksare absent. Preferably, intensity shifts, complete filtering, anddifferent dampening effects are identified through using a type ofcalibration light having a continuum of intensity which provides a morecomplete picture than the case where a calibration light having discreteintensity peaks is used for any of these purposes. That is, little or noinformation is provided on the "behavior" of the window in relation tothose wavelengths which are located between the intensity peaks in thecalibration light (i.e., the effect of the window on the intensity ofthese wavelengths), and therefore assumptions must be made. There is noneed for such assumptions in the case of using a calibration light witha continuum of intensity for the above-noted purposes.

A third aspect of the present invention is directed to monitoring aplasma process through initializing a plasma monitoring assembly. Theplasma monitoring assembly evaluates at least one aspect of a subjectplasma process (e.g., one currently being conducted within a processingchamber) by obtaining optical emissions data through a window on theprocessing chamber. Optical emissions which are obtained on the subjectplasma process include at least wavelengths from about 250 nanometers toabout 1,000 nanometers which defines a first wavelength range, and atleast at every 1 nanometer throughout this first wavelength range.

Initialization of the plasma monitoring assembly in a first embodimentof this third aspect includes directing a calibration light toward thewindow through which optical emissions are obtained, reflecting a firstportion of the calibration light from the window, and comparing theoriginal calibration light which was sent with this first portion.Consequently, any combination of the various features discussed above inrelation to calibration in accordance with the first and second aspectsmay be implemented in this third aspect as well. When the comparison ofthe calibration light with the first portion of the reflected lightyields a first result (e.g., an intensity shift(s), a wavelength shift,filtering, or any combination thereof), at least one adjustment is madein relation to the plasma monitoring assembly.

Adjustments which may be made in relation to the plasma monitoringassembly in this first embodiment of this third aspect include physicaladjustments to the plasma monitoring assembly. For instance, in the casewhere a spectrometer assembly is used to obtain optical emissions dataand includes at least one scanning type spectrometer, the grating, oneor more of its mirrors, or both may be moved (e.g., pivoted) tocalibrate the plasma monitoring assembly. Any calibration of the plasmamonitoring assembly involving a physical adjustment of the spectrometerassembly in this manner will typically be to address a wavelength shiftwhich is typically due to "drifting" of the spectrometer assembly,although this type of physical adjustment may be used to addresswavelength shifts from other sources. Another type of adjustment whichmay be made in relation to the plasma monitoring assembly is acalibration of the optical emissions which are collected or obtained onthe subject plasma process, or more typically data which isrepresentative of these optical emissions. In this regard, the"adjustment" may include the implementation of a single calibrationfactor or multiple calibration factors in the plasma monitoringassembly. A single calibration factor is typically utilized when thereis a "uniform" intensity shift across the optical emissions to beevaluated (e.g., ±"x" intensity units possibly being considered"uniform"), whereas multiple calibration factors are typically utilizedwhen there is a different degree of dampening across the opticalemissions to be evaluated. The calibration factor(s) may then beimplemented to have the desired effect on the output of the spectrometerassembly. Another way to calibrate in this manner is to normalize theoptical emissions to be evaluated (or data representative thereof) basedupon the comparison of the calibration light and the first portion ofthe calibration light reflected by the window.

Initialization of the plasma monitoring assembly in a second embodimentof this third aspect includes the steps of monitoring the window on theprocessing chamber through which optical emissions are obtained. Thesecond embodiment further includes the step of determining if the windowis filtering out optical emissions within a first wavelength regionwhich is contained within the first wavelength range of about 250nanometers to about 1,000 nanometers, which again defines the opticalemissions being obtained and made available for evaluation by the plasmamonitoring assembly. As such, the various features discussed above inrelation to the second aspect of the invention in relation to"filtering" may be included in this second embodiment of the thirdaspect as well. Finally, the second embodiment of the third aspectincludes the step of having the plasma monitoring assembly ignore anyoptical emissions within any first wavelength region or that region(s)where filtering has been detected. Notification may be provided that afiltering condition has been identified. Moreover, a recommendation thatthe window be replaced may be issued in this situation.

The monitoring step of the second embodiment of the third aspect mayinclude the step of directing a calibration light toward the window,reflecting a first portion of this calibration light from the window,and comparing the calibration light with this first portion. As such,any one or more of the features discussed above in relation to the firstand second aspects of the present invention may be utilized by thissecond embodiment of the third aspect as well. The second embodiment mayalso include the step of making at least one adjustment in relation tothe plasma monitoring assembly when certain conditions are identified bythe above-noted calibration procedure. As such, any one or more of thefeatures discussed above in relation to the first embodiment of thisthird aspect may also be utilized by this second embodiment of the thirdaspect of the present invention.

Initialization of the plasma monitoring assembly in a third embodimentof the above-noted third aspect of the present invention includes thesteps of monitoring the window on the processing chamber through whichoptical emissions on the subject plasma process are obtained. The thirdembodiment further includes the step of determining if the window ishaving a first effect g(e.g., dampening) on a first wavelength regionwhich is contained within the first wavelength range of about 250nanometers to about 1,000 nanometers (which defines the opticalemissions being obtained and made available for evaluation by the plasmamonitoring assembly), as well as a second effect (e.g., dampening) on asecond wavelength region which is also contained within the firstwavelength range but outside of the first wavelength region associatedwith the first effect. As such, the various features discussed above inrelation to the second aspect of the invention in relation toidentifying different dampening effects may be included in this thirdembodiment of the third aspect as well. Finally, the third embodiment ofthe third aspect includes the step of making at least one adjustment inrelation to the plasma monitoring assembly if any of these first andsecond types of effects are identified. As such, any one or more of thefeatures discussed above in relation to the first embodiment of thethird aspect may be utilized by this third embodiment of the thirdaspect as well.

The monitoring step of the third embodiment of the third aspect mayinclude the step of directing a calibration light toward the window,reflecting a first portion of this calibration light from the window,and comparing the calibration light with this first portion. As such,any one or more of the features discussed above in relation to the firstand second aspects of the present invention may be utilized by thisthird embodiment of the third aspect as well. The third embodiment mayalso include the step of making at least one adjustment in relation tothe plasma monitoring assembly when certain conditions are identified bythe above-noted calibration procedure. As such, any one or more of thefeatures discussed above in relation to the first embodiment of thisthird aspect may also be utilized by this third embodiment of the thirdaspect of the present invention.

A fourth aspect of the present invention relates to a method formonitoring a plasma process which includes monitoring a window on theprocessing chamber in which the plasma process is conducted. In thisregard, a quantity of product is loaded into the processing chamber(e.g., at least one wafer), the plasma process is thereafter conductedon this product (e.g., a plasma recipe), and data on the plasma process(e.g., optical emissions of the plasma in the chamber during theprocess) is obtained through the window on the processing chamber. Theplasma process is evaluated based upon both the data which is obtainedthrough the processing chamber window and the monitoring of the window.

In a first embodiment of the above-noted fourth aspect, the monitoringof the window more specifically includes the step of monitoring anactual condition of the window. The condition of the window in the caseof the subject second embodiment is monitored other than through datawhich is obtained on the plasma process. That is, the data which isobtained on the plasma process being conducted within the processingchamber is not utilized in any manner by the step of monitoring thecondition of the window in this first embodiment of the fourth aspect ofthe present invention.

Various features may be utilized by the above-noted first embodiment ofthe fourth aspect of the present invention, and these features may beused alone in the above-noted first embodiment as well as in anycombination. Monitoring of the condition of the window during executionof the plasma process within the chamber may be prohibited as anadditional feature of the subject first embodiment. That is, themonitoring of the condition of the window and the running of the plasmaprocess may be executed at different and non-overlapping times.Typically, the monitoring of the condition of the window will be doneprior to running of the subject plasma process within the chamber todetermine the effect that the inner surface of the window will have onthe subject plasma process data which is obtained through the window. Assuch, one or more of the features discussed above in relation to thesecond aspect of the present invention on "identifiable conditions"(e.g., wavelength shift, intensity shift, filtering, "uniform" dampeningeffects (intensity), multiple dampening effects (intensity)), as well ashow these conditions may be identified (e.g., sending a calibrationlight toward the window and comparing this light with that portion ofthe calibration light which is reflected by the inner surface of thewindow), may be implemented in this first embodiment of fourth aspect ofthe present invention as well. At least one adjustment may be made inrelation to the plasma monitoring assembly once one or more of these"conditions" is identified. The various types of "adjustments" areaddressed above in relation to the third aspect of the presentinvention, and any one or more of those features may be included in thisfirst embodiment of the fourth aspect as well.

A second embodiment of the subject fourth aspect characterizes themonitoring of the window in a different manner than as discussed abovein relation to the first embodiment. In this regard, the monitoring stepof this second embodiment includes the steps of directing a calibrationlight toward the window, reflecting a first portion of this calibrationlight from the inner surface of the window, and comparing thecalibration light as it was sent to the window with that portion of thecalibration light which was reflected by the inner surface of thewindow. As such, one or more of the features presented above in relationto the first and second aspects of the invention may be included in thissecond embodiment of the fourth aspect as well. The types of conditionswhich may be identified through this monitoring of the processingchamber window are presented above in relation to the second aspect ofthe present invention, and any one or more of these features may beincluded in this second embodiment of the fourth aspect as well.

A fifth aspect of the present invention relates to determining whenplasma exists or is "on" within a processing chamber based uponmachine-based optical analysis (i.e., not by a human eye). Morespecifically, the fifth aspect relates to obtaining optical emissionsfrom within the processing chamber, evaluating these optical emissions,generating a plasma in the processing chamber, and identifying whenplasma exists within the processing chamber through a machine-basedevaluation of the optical emissions from within the processing chamber.

Various features may be utilized by the above-noted fifth aspect of thepresent invention, and these features may be used alone as well as inany combination. For instance, the identification of when plasma existswithin the chamber through optical analysis may implement varioustechniques. The time at which the plasma comes on within the chamber maybe identified by determining when the optical emissions from within theprocessing chamber exceeds a certain predetermined output (e.g., whenthe intensity of the optical emissions or a certain portion thereofwithin the chamber exceeds a certain amount). The identification of whenplasma exists through optical analysis may also be directed towardevaluating how the optical emissions change over time. For instance,when no plasma exists within the chamber, there will be no correspondingoptical emissions being emitted from the chamber. Therefore, theidentifying step may simply be directed toward noting any change from a"dark" condition to a "light" condition. Another way to determine whenplasma exists within the chamber through an optical analysis is todetermine when the optical emissions from within the chamber include atleast a certain number of discrete intensity peaks, each of which has atleast a certain intensity. Finally, the presence of plasma within thechamber may be identified by determining when the current opticalemissions from within the chamber match at least one output recorded ona computer-readable medium which was previously obtained from thechamber at a time when plasma was known to exist within the chamber.

Another feature which may be incorporated in the subject fifth aspectrelates to the processing of a product after the plasma exists withinthe chamber. In one embodiment, the window on the chamber may bemonitored in accordance with the fourth aspect of the inventiondiscussed above. These monitoring operations may be automaticallyterminated at a time when plasma is first identified within the chamberthrough the noted optical analysis provided by this fifth aspect. Inanother embodiment, plasma processes conducted within the chamber may bemonitored by a plasma monitoring assembly. Calibration of this plasmamonitoring assembly may be made available in accordance with the thirdaspect of the invention discussed above. These calibration operationsmay be automatically terminated when plasma is identified within thechamber through the noted optical analysis provided by this fifthaspect.

A sixth aspect of the present invention relates to a plasma spectradirectory which contains at least optical emissions data from plasmaprocesses previously conducted within the processing chamber and whichare used to evaluate plasma processes subsequently conducted in thisvery same processing chamber. The plasma spectra directory is stored ona computer-readable storage medium and for ease of description includesa first data structure having a plurality of data entries. Each of thesedata entries includes data representative of optical emissions from atleast one time during the subject plasma process, and this data isassociated with one of a first category, a second category, and a thirdcategory.

The data entries associated with the first category are those plasmaprocesses which have been run in the chamber and which define a"standard" against which subsequent plasma processes are judged. Plasmaprocesses which are run in the processing chamber are evaluated todetermine if they "correspond" or "match" with at least one data entryassociated with the first category. These types of plasma processesassociated with the first category thereby may be characterized as"normal" runs. In this case, plasma processes which are associated withthe first category are at least assumed to have proceeded withoutsubstantially any error, and may be tested in some manner to confirmthat they did in fact proceed without any substantial error oraberration.

The optical emissions of the plasma in the processing chamber willtypically reflect whether a given plasma process is proceeding in a"normal" fashion. In this regard, optical emissions associated with adata entry of the first category preferably include at least wavelengthsfrom about 250 nanometers to about 1,000 nanometers at least at every 1nanometer throughout this range and at least at every 1 second from thesubject plasma process. Although evaluations of plasma processessubsequently conducted in the subject processing chamber need notutilize all of this data, it will be available if desired/required.Moreover, typically data on the entirety of the subject plasma process,or at least that portion of the process after the plasma has stabilized,is included in data entries associated with the first category.

Virtually any type of plasma process may be included in data entriesassociated with the first category as long as its optical emissions dataprovides an indication that the plasma process is proceeding in acertain fashion. One or more plasma recipes (run on production wafers,qualification wafers, or both), plasma cleanings (before or after a wetclean), and conditioning wafer operations may each be included in theplasma spectra directory and associated with the first category.Multiple "species" of these types of plasma processes may also beincluded in the plasma spectra directory in association with the firstcategory (e.g., different types of plasma recipes). Multiple dataentries of the same "species" may also be included in the plasma spectradirectory in association with the first category as well (e.g., multipleentries of the same plasma recipe run on the same type of product).

The data entries associated with the second category of the subjectsixth aspect are those plasma processes (e.g., plasma recipes, plasmacleans, conditioning wafer operations) which have been run in theprocessing chamber and which have encountered at least one error oraberration. This error or aberration will typically be represented by achange in the optical emissions of the plasma in the processing chamber,and the cause may be identified by a review of these optical emissions.Typically this review is after termination of the subject plasmaprocess. Obtaining optical emissions data within the above-notedwavelength range increases the likelihood that optical emissions datawhich is representative of the error or aberration will in fact beavailable for inclusion in a data entry which is associated with thesecond category.

The identification or cause of the error or aberration is included insome manner with the data entry which is associated with the secondcategory. Various actions may be initiated based upon this information.An alert or the like (audio, visual, or both) may be issued to apprisepersonnel that an error has been encountered in the subject plasmaprocess in the subject processing chamber. Specific information on theerror may also be made available, as well as one or more ways to addressor correct the error or aberration. Finally, corrective actions may beautomatically undertaken if desired.

Typically, the entire run in which the error occurred is not included inthe data entry associated with the second category. Instead, only thoseoptical emissions which reflect the existence of the subject error oraberration are typically included in such a data entry. This may includeoptical emissions data from only a single point in time during thesubject plasma process or from multiple times. Optical emissionsincluded in any data entry associated with the second category may alsobe of the above-noted wavelength range. However, if the error oraberration is only reflected in a certain portion of the opticalemissions which are obtained on the subject plasma process, only thisportion need be included in the plasma spectra directory for the subjectdata entry associated with the second category.

The data entries associated with the third category in relation to thesubject sixth aspect are those plasma processes which have been run inthe processing chamber and which are "unknown" to the plasma spectrasubdirectory. That is, the optical emissions from the subject plasmaprocess have failed to correspond with any data entry associated withthe first category or with the second category. Moreover the reason asto why this is the case has yet to be determined, or more accurately thecause has yet to be associated with a data entry on thecomputer-readable storage medium. Two situations will typicallyencompass each case where a data entry is recorded in the plasma spectradirectory and associated with the third category. Plasma processes whichhave not yet been recorded in the plasma spectra directory andassociated with the first category are one such situation. In this case,the entirety of the subject plasma process may be recorded in the plasmaspectra directory and associated with the third category. Once this dataentry is identified as being a new plasma process which did or wasassumed to have proceeded without substantially any error or aberration,the data entry may be "transferred" from the third category to the firstcategory. Plasma processes which have encountered an error which has notbeen recorded in the plasma spectra directory and associated with thesecond category will also be recorded in a data entry under the thirdcategory. Typically, only data from the initial occurrence of the erroror aberration until the end of the plasma process will be recorded in adata entry associated with the third category in this situation.Subsequent evaluation of the optical emissions data from this plasmaprocess may reveal that a "new" error was encountered. If the cause ofthe error is identified, all or a portion of the data from the subjectdata entry associated with the third category may then be "transferred"to the second category.

A seventh aspect of the present invention relates to various analyticaltechniques which may be used to evaluate a plasma process in at leastsome manner. In a first embodiment of this seventh aspect, acomputer-readable storage medium includes a plurality of data entries.At least one of these data entries is associated with the type of firstcategory discussed above in relation to the sixth aspect, while at leastone of these data entries is associated with the type of second categoryalso discussed above in relation to the sixth aspect. The evaluationtechnique embodied by this first embodiment of the seventh aspect firstdetermines if the subject plasma process corresponds with any data entryassociated with the first category. Any such correspondence may be usedto characterize the subject plasma process as "normal" or the like. Ifthe subject plasma process at any time fails to correspond with at leastone data entry under the first category, this first embodiment of theseventh aspect will then "search" those data entries under the secondcategory to see if the subject plasma process has encountered a knownerror or aberration. Therefore, data entries under the second categoryare not searched in each case.

Various features may be utilized by the above-noted first embodiment ofthe seventh aspect of the present invention, and these features may beused alone in the above-noted first embodiment as well as in anycombination. Initially, each of the various features/concepts discussedabove in relation to the sixth aspect are equally applicable to and maybe incorporated in this first embodiment of the subject seventh aspect.There are also various ways of determining whether the optical emissionsdata of the subject plasma process conforms or corresponds with a givendata entry. Conformance or correspondence may be based upon determiningif the pattern of the current optical emissions is a "match" with thepattern of the relevant optical emissions from the data entry. What arethe "relevant" optical emissions may also be subject to a number ofcharacterizations. For instance, the time associated with the currentoptical emissions may be used as a criterion to determine whether theseemissions correspond with a given data entry. That is, the time at whichthe subject optical emissions were obtained would be used to identifywhich optical emissions from a given data entry would be used for thesubject comparison (i.e., select the optical emissions from the dataentry which were obtained at the same time as the subject opticalemissions). Alternatively, the subject plasma process may simply beevaluated to determine if it is progressing in the same fashion as atleast one of the data entries associated with the first category,although not necessarily at the same rate. Time would not be a limitingcriterion in this case.

Various actions may be initiated if the current plasma processcorresponds with a data entry associated with the second category,either manually or automatically. For instance, the subject plasmaprocess may be terminated, an alert may be issued that an error has beenencountered, further use of the processing chamber for processingproduct may be suspended, adjustment of the plasma process may beundertaken in an attempt to remedy the subject error(s), or anycombination thereof.

A second embodiment of the subject seventh aspect utilizes acomputer-readable storage medium which includes a first data entry whichis associated with a first category of the type identified above inrelation to the sixth aspect. This data entry includes a plurality offirst data segments from a plurality of different times during oneplasma process previously conducted in the processing chamber. Each datasegment includes optical emissions of the plasma in the chamber forwavelengths of at least about 250 nanometers to about 1,000 nanometerswhich defines a first wavelength range, and at least at every 1nanometer throughout this first wavelength range. This second embodimententails obtaining current optical emissions from another plasma processrun in this same processing chamber which are also within the firstwavelength range and at least at every 1 nanometer throughout this firstwavelength range. A comparison is undertaken between the current opticalemissions and those associated with at least one first data segment ofthe first data entry throughout the first wavelength range and at leastat every 1 nanometer throughout the first wavelength range. The featuresdiscussed in relation to this second embodiment may be incorporated withthose discussed above in relation to the first embodiment of the subjectseventh aspect.

A third embodiment of the subject seventh aspect also utilizes acomputer-readable storage medium. A first plasma process is run in theprocessing chamber. Optical emissions of the plasma in the chamber areobtained for wavelengths of at least about 250 nanometers to about 1,000nanometers which defines a first wavelength range, and at least at every1 nanometer throughout this first wavelength range. This data isobtained at a plurality of times during this first plasma process andsuch is recorded in a first data entry on the computer-readable storagemedium. A second plasma process is conducted after termination of thefirst and similar data is obtained. The second plasma process isevaluated based upon at least a portion of the optical emissions datafrom the second plasma process. In some cases it may be desirable tocompare the optical emissions from the second plasma process with thoseoptical emissions from the first plasma process throughout the entiretyof the first wavelength range and at least at every 1 nanometerthroughout this first wavelength range. However, in some cases this maynot be practical, desirable, or necessary. In this regard, the progressof the second plasma process in relation to the first plasma processrecorded in the first data entry on the computer-readable storage mediummay be based upon an evaluation of at least a 50 nanometer bandwidth andat least every 1 nanometer throughout this smaller bandwidth.

A smaller wavelength region may be selected for evaluating the secondplasma process in relation to the first plasma process in a variety ofmanners. The particular wavelength(s) at which error(s) have beenpreviously encountered in running this same plasma process may be usedto select that portion of the first wavelength range which should beused in the subject evaluation (e.g., ±25 nanometers of each wavelengthwhich is indicative of an error or aberration). Moreover, a wavelengthregion may be selected which includes each of the errors previouslyencountered on the same type of plasma process. The "width" of theregion may be defined by the two extreme wavelengths, although it wouldbe preferred to include a "buffer" of sorts on each of these ends (e.g.,expand the range by 25 nanometers on each end). Finally, the particularwavelength(s) which is indicative of the endpoint of the subject plasmaprocess or discrete/discernible portion thereof may be used to selectthat portion of the first wavelength range which should be used in thesubject evaluation (±25 nanometers of each such wavelength). Individualendpoint indicator wavelengths are discussed in more detail below inrelation to the ninth aspect of the present invention.

An eighth aspect of the present invention relates to identifying thetype of plasma process conducted within the processing chamber. Thisaspect may be used to identify whether a plasma process is a certaintype of plasma recipe being run on a certain type of production wafer, acertain type of plasma recipe being run on a certain type ofqualification wafer, a certain type of plasma recipe being run on acertain type of conditioning wafer, or a plasma clean being run in achamber. A first embodiment of this eighth aspect is able to identifythe particular type of a plasma recipe being run on product (e.g.,production wafer, qualification wafer) in a processing chamber basedupon the storage of at least two plasma recipes on a computer-readablestorage medium. In this regard, the computer-readable storage mediumincludes a plurality of data entries. A first of these data entriesincludes relevant data from a plurality of times during a first plasmarecipe run on product in the processing chamber (and preferably of theentirety of this first plasma recipe at least after stabilization of theplasma). A second of these data entries includes relevant data from aplurality of times during a second plasma recipe (different from thefirst plasma recipe) run on product in the same processing chamber (andpreferably of the entirety of this second plasma recipe at least afterstabilization of the plasma). Data on a subject plasma recipe which isbeing run on product in the same processing chamber is obtained. Thisdata is used to determine if the current plasma recipe is of the sametype as the first or second plasma recipe stored on thecomputer-readable storage medium. Preferably, this determination iscompleted prior to termination of the current plasma recipe and at leastbefore the next product is loaded into the chamber. This firstembodiment of the eighth aspect may be used to determine not only theidentity of the subject plasma process, but the type of product (e.g.,whether a production wafer or a qualification wafer) that is beingprocessed by including relevant data from prior plasma processes on thecomputer-readable storage medium. That is, by including a plasma recipe"A" run on a certain type of production wafer in one data entry and thesame plasma recipe "A" on a certain type of qualification wafer inanother data entry, the ability exists to determine if the currentplasma recipe is being run on a production versus a qualification wafer.

Various features may be utilized by the above-noted first embodiment ofthe eighth aspect of the present invention, and these features may beused alone in the above-noted first embodiment as well as in anycombination. Initially, the data obtained on the current plasma processmay be optical emissions of the plasma in the processing chamber. Theseoptical emissions may include at least wavelengths from about 250nanometers to about 1,000 nanometers (inclusive) which defines a firstwavelength range, and optical emissions may be obtained at least atevery 1 nanometer throughout this first wavelength range. Opticalemissions of the subject plasma process may be compared with one or bothof the first and second plasma recipes stored on the computer-readablestorage medium to see if there is sufficient correspondencetherebetween. As such, the techniques discussed above in relation to theseventh aspect may be implemented in this first embodiment of the eighthaspect as well.

A second embodiment of the subject eighth aspect is directed towardinputting the plasma recipe to be run in the chamber and using theprinciples discussed above in relation to the first embodiment of theeighth aspect to verify that no errors were made when inputting thesubject plasma recipe. That is, the identify of the subject plasmaprocess is determined in accordance with the first embodiment of thiseighth aspect. Therefore, each of the various features discussed abovein relation to the first embodiment of the eighth aspect may beincorporated in this second embodiment of the eighth aspect as well. Theidentification of the subject plasma process through optical analysis inaccordance with the foregoing is then conveyed in some manner to theappropriate personnel (e.g., on a display). If the wrong plasma processwas input for a certain wafer or "lot" of wafers, the identification ofthe subject plasma process and the conveyance of this identity to theappropriate personnel would apprise the personnel of this situation.

A third embodiment of the subject eighth aspect is directed toidentifying a subject plasma recipe based upon at least two plasmarecipes which are stored on a computer-readable storage medium and whichwere previously run in the same processing chamber. The first executionof the subject plasma recipe is initiated and is of the type associatedwith either the first or second plasma recipe. At least onecharacteristic of the plasma is monitored during the execution of eachsubject plasma recipe. Both the first and second plasma recipes areavailable for comparison against the first execution of the subjectplasma recipe. However, after the first execution of plasma recipe isidentified as being either the first or second plasma recipe from thecomputer-readable storage medium (identified plasma recipe), subsequentexecutions of the subject plasma recipes are evaluated at leastinitially only in relation to the identified plasma recipe on thecomputer-readable storage medium. This embodiment is particularlypertinent to the case where the first wafer of a cassette or boat ofwafers is evaluated in accordance with the foregoing since the sameplasma recipe is typically run on the entire cassette. Therefore, oncethe third embodiment of the eighth aspect determines the identify of theplasma recipe being run on the first wafer, all subsequent wafers in thecassette are at least initially evaluated against only one plasma recipeon the computer-readable storage medium. Enhanced evaluation speedtherefore may be realized. If any such subsequent executions of thesubject plasma recipe deviate from the identified plasma recipe on thecomputer-readable storage medium, one variation of this thirdembodiments makes other plasma recipes on the computer-readable storagemedium available for evaluation of the then current plasma recipe.Another possibility would be to check for any data entry of the sameplasma recipe that was run on a qualification wafer versus a productionwafer if there was a failure of the current plasma recipe to correspondwith the plasma recipe stored on the computer-readable storage medium(i.e., assuming that the first wafer was a production wafer and had itsplasma recipe identified). In this case, the logic would be to evaluatethe entire cassette first against the plasma recipe for the productionwafer stored on the computer-readable storage medium, and then againstthe same plasma recipe but for a qualification wafer stored on thecomputer-readable storage medium if necessary.

A ninth aspect of the present invention relates to engaging in researchto identify one or more indicators of a first endpoint which is when theplasma process (e.g., plasma recipe, plasma clean, conditioning waferoperation) or portion thereof (e.g., plasma step of a plasma recipe) hasachieved a first predetermined result (e.g., the etching away of acertain layer from a multi-layer structure such as a wafer). In thisregard, a first plasma process is run in the processing chamber. Opticalemissions of the plasma are obtained at a plurality of times during thisfirst plasma process. These optical emissions include at leastwavelengths from about 250 nanometers to about 1,000 nanometers(inclusive) which defines a first wavelength range. Optical emissionsare preferably obtained at least at every 1 nanometer throughout thisfirst wavelength range. These optical emissions are evaluated oranalyzed and at least one endpoint indicator is selected based upon thisanalysis.

Various features may be utilized by the ninth aspect of the presentinvention, and these features may be used alone in relation to thisninth aspect as well as in any combination. For instance, the subjectanalysis may include generating a plot of intensity versus time for aplurality of individual wavelengths which are within the firstwavelength range. Preferably, plots are generated for each wavelengthwhich is available based upon the data collecting resolution of therelevant "collecting" structure (e.g., spectrometer(s)). These plots areanalyzed after the conclusion of the running of the plasma process,preferably in view of information as to about what time the firstendpoint should have occurred (e.g., calculated based upon knowledge ofprocess conditions and thickness of layer to be etched away). Anywavelength having a plot with a distinctive change in intensity aroundthat time where the first endpoint should have occurred may beidentified as a possible endpoint indicator candidate.

Further features of the subject ninth aspect relate to the above-notedplots. Initially, the use of the above-described methodology requires noknowledge of the chemistry involved in the subject plasma process.Instead, data is taken over a large wavelength range and at a datacollecting resolution which should include at least one indicator of thefirst endpoint (e.g., at least one specific wavelength which undergoes achange which corresponds with the occurrence of the first endpoint). Apattern of the plot(s)of the individual wavelength(s) which is selectedas being a possible candidate for an endpoint indicator of the firstendpoint may in turn be used as the endpoint indicator. Moreover, thesubject plot may be defined by an equation or function up to that timeat which the first endpoint occurs (e.g., a linear function, a firstorder polynomial, a second order polynomial). When the current plasmarecipe no longer "fits" this function, endpoint may be called. First andsecond derivatives of this function may provide for a more expeditiousdetermination of endpoint and are contemplated by this ninth aspect aswell.

Multiple executions of the same plasma process may be required toincrease the confidence level associated with the endpoint indicatorswhich are selected as being indicative of the first endpoint. When theabove-noted plots are used, a comparison of the plots between two ormore runs may identify a pattern which stays the same, but whichundergoes some type of change. This change may be a temporal shift, ashift in the intensity associated with the pattern, a uniformenlargement of the pattern, a uniform reduction in the pattern, or anycombination thereof. Patterns which undergo this type of change are anindicator that the corresponding wavelength is in fact indicative of thefirst endpoint. One "controlled" way of inducing such a shift is toprocess two or more products having different thicknesses. There shouldbe a temporal shift if the particular wavelength is in fact indicativeof the first endpoint in this case. That is, the corresponding plotshould have a change which shifts in accordance with the change inthickness.

The analysis used to select at least one indicator of the first endpointmay also include examining the optical emissions to identify theexistence of intensity peaks, and determining if any of these intensitypeaks at least substantially disappear at about a time where the firstendpoint should occur. Any such wavelength associated with these typesof intensity peaks may be an indicator of the first endpoint. Similarly,the analysis used to select at least one indicator of the first endpointmay include examining the optical emissions to determine if anyintensity peaks develop at about a time when the first endpoint shouldoccur. Any such wavelength associated with these types of intensitypeaks may also be an indicator of the first endpoint. In addition, theanalysis used to select at least one indicator of the first endpoint mayinclude examining the optical emissions to determine if any intensitypeak reaches a steady state at about a time when the first endpointshould occur. Any such wavelength associated with these types ofintensity peaks may also be an indicator of the first endpoint. Finally,the analysis used to select at least one indicator of the first endpointmay include examining the optical emissions to determine if anyintensity peak, which has been at a steady state, undergoes change atabout a time when the first endpoint should have occurred. Any suchwavelength associated with these types of intensity peaks may also be anindicator of the first endpoint. Any combination of the foregoing may beused to select an endpoint indicator.

A tenth aspect of the present invention relates to monitoring at leasttwo aspects of a plasma process, one of which may be the "health" of theplasma process and another of which may be at least one endpointassociated with the plasma process. This tenth aspect is applicable toany plasma process, including plasma recipes which are run on product(e.g., production wafers, qualification wafers) in a processing chamber,plasma cleanings (e.g., with or without a wet clean), and conditioningwafer operations.

By further way of introduction, substantially the entirety of the plasmaprocess may be evaluated in relation to its "health", except possiblythe initial portion of the plasma process where the plasma is typicallyunstable. In contrast, the evaluation of the plasma process in relationto identifying an endpoint need not be initiated until closer to thetime at which the subject endpoint should be reached. Moreover, thefrequency at which the plasma health is evaluated need not be the sameas the frequency at which the evaluation is undertaken to identify thesubject endpoint. For instance, the plasma health may be assessed lessfrequently than the evaluation relating to identifying the subjectendpoint.

In a first embodiment of the above-noted tenth aspect, a plasma processis conducted within the processing chamber and at least a first endpointis associated with this plasma process. The plasma process is monitoredto identify the occurrence of the first endpoint. Any endpoint detectiontechnique may be used for this first embodiment of the tenth aspect,including those addressed below in relation to the eleventh through thethirteenth aspects of the present invention. The "condition" of theplasma is also evaluated during, and more preferably throughout theentirety of, the plasma process (again excluding possibly the initialportion when the plasma is typically unstable). One way of defining the"condition" associated with this first embodiment of the tenth aspect isequating the same with the cumulative result of all parameters having aneffect on the plasma in the processing chamber. This may be done byevaluating optical emissions of the plasma in the chamber which includesat least wavelengths from about 250 nanometers to about 1,000 nanometerswhich defines a first wavelength range, and at least at every 1nanometer throughout this first wavelength range and at least at aplurality of different times during the subject plasma process. Anotherway of characterizing the monitoring of the "health" of the currentplasma process is to determine if it is proceeding in accordance with atleast one plasma process previously conducted within the same processingchamber. Therefore, the features discussed above in relation to theseventh aspect of the present invention may be utilized in this tenthaspect of the present invention as well.

A second embodiment of this tenth aspect involves generating a plasma inthe processing chamber and running a first plasma step in the chamber.Associated with this first plasma step is a first endpoint which is whenthe first plasma step has produced a first predetermined result. Atleast one characteristic of the plasma in the chamber is evaluatedduring the first plasma step using a first time resolution. Althoughtypically equal increments will be utilized in this evaluation, such isnot required by this second embodiment of the tenth aspect. Anevaluation is also undertaken to identify an occurrence of the firstendpoint using a second time resolution which is different than thefirst. The above-noted "at least one characteristic" may be thecondition of the plasma during the subject plasma process, although itneed not be the case.

An eleventh aspect of the present invention generally relates tomonitoring a plasma process to identify an occurrence of a firstendpoint associated with the plasma process. More specifically, at leasttwo different techniques are used to evaluate the current plasma processto identify the first endpoint in this eleventh aspect. Endpoint may becalled when only one of these techniques identifies the occurrence ofthe first endpoint, or may be called after each of these techniquesidentifies the occurrence of the first endpoint. This eleventh aspect ofthe present invention is applicable to any plasma process having atleast one endpoint associated therewith (e.g., plasma recipes which arerun on product in a processing chamber, plasma cleanings, andconditioning wafer operations).

One of the techniques which may be used in the subject eleventh aspectinvolves a comparison of the current optical emissions of the plasma inthe chamber with optical emissions of the plasma in the chamber from aprevious time in the same process, preferably the immediately precedingtime at which optical emissions were obtained. In one embodiment, theseoptical emissions include at least wavelengths from about 250 nanometersto about 1,000 nanometers at least at about every 1 nanometer. Whenthese optical emissions are substantially a "match" (e.g., when thedifferential of the pattern of current optical emissions and the patternof previous-in-time optical emissions is substantially free of peaks),particularly after an initial portion of the plasma has been completed,endpoint may be deemed to have been reached. Stated another way, whenthere is no longer any substantial change in the optical emissions,endpoint may be deemed to have been reached.

Another technique for identifying endpoint which may be used in thesubject eleventh aspect involves a comparison of the current opticalemissions of the plasma in the chamber with a standard. This "standard"may be optical emissions of the plasma in the chamber from a previousexecution of this same plasma process in the same processing chamber ata time when endpoint was at least deemed to have been reached. Moreover,this standard may be stored on a computer-readable storage medium. Inone embodiment, these optical emissions include at least wavelengthsfrom about 250 nanometers to about 1,000 nanometers at least at aboutevery 1 nanometer. When these optical emissions are substantially a"match" (e.g., when the differential of the pattern of current opticalemissions and the pattern of previous-in-time optical emissions issubstantially free of peaks), particularly after an initial portion ofthe plasma has been completed, endpoint may be deemed to have beenreached.

Yet another technique which may be used in the subject eleventh aspectof the present invention includes determining if there is at least afirst change in the impedance of the processing chamber which isreflected in the optical emissions of the plasma in the processingchamber. A "modal" change in the plasma may be indicative of a change inimpedance which in turn is indicative of endpoint. This "modal" changemay be a rather sudden and significant increase or decrease in theintensity of the entirety of the plasma or of a particularwavelength(s).

Another technique which may be used to identify endpoint in relation tothe subject eleventh aspect includes evaluating at least one individualwavelength of light forming the plasma of the subject plasma process.This one wavelength of light may be evaluated to determine when a plotof intensity versus time deviates by more than a predetermined amountfrom a predetermined equation (e.g., when there is no longer a "fit"between the current data and the subject equation). Therefore, thefeatures discussed above in relation to the ninth aspect of the presentinvention are also relevant to this portion of the eleventh aspect aswell. Moreover, any one or more individual wavelengths of light may beevaluated to determine when the change in slope over time of thewavelength(s) changes by more than a predetermined amount. Second orderderivatives may be used as well.

A twelfth aspect of the present invention is directed toward a techniquefor identifying the occurrence of a first endpoint associated with aplasma process (e.g., plasma recipe, plasma clean, conditioning waferoperation) or a discrete/discernible portion thereof (e.g., a plasmastep of a multiple step recipe or process). Optical emissions of theplasma in the chamber from the process are obtained. These opticalemissions include at least wavelengths from about 250 nanometers toabout 1,000 nanometers which defines a first wavelength range. The dataresolution which is used in collecting the optical emissions is no morethan about 1 nanometer. This means that optical emissions are obtainedat least at every 1 nanometer throughout the first wavelength range.

Identification of the first endpoint involves a comparison of the mostcurrent optical emissions of the plasma in the chamber with a firstoutput. This first output may be optical emissions of the plasma in thechamber from a previous time in the same plasma process, preferably theimmediately preceding time at which the optical emissions were obtainedin relation to the now current optical emissions. This first output mayalso be optical emissions from the same type of plasma process which waspreviously conducted in the same processing at a time when endpointshould have occurred. In this case the first output could be stored on acomputer-readable storage medium. When the above-noted comparisonindicates that the current optical emissions and the first output are atleast substantially a "match", particularly after an initial portion ofthe plasma has been completed, the first endpoint is deemed to have beenreached. Confidence in the calling of the first endpoint by theabove-noted technique may be enhanced by using a second technique andnot calling the first endpoint until both of the techniques have "seen"the first endpoint. Any of the techniques discussed above in relation tothe eleventh aspect of the invention may be utilized in this twelfthaspect for this purpose.

A thirteenth aspect of the present invention relates to identifying theoccurrence of multiple endpoints in a single plasma process. Many plasmarecipes will include a number of different plasma steps. Each of theseplasma steps typically has an identifiable endpoint associatedtherewith. Therefore, the eleventh aspect of the present inventionallows for the identification of at least two of these endpoints andincluding each endpoint associated with the subject plasma process. Eachof the techniques identified in eleventh aspect discussed above may beutilized in this thirteenth aspect.

When to clean a processing chamber is the subject of the fourteenthaspect of the present invention. Product is loaded in the processingchamber. The processing chamber is sealed and a first plasma process isthereafter run on the product. Data relating to the plasma process isobtained. From this data a determination is made regarding the conditionof the chamber. Specifically, a determination is made as to whether theinterior of the chamber is sufficiently "dirty" from plasma processespreviously run in the chamber to warrant cleaning the chamber. Personnelmay be notified, actions may be initiated, or both, if this "dirtychamber" condition is identified. Appropriate actions includeterminating the current plasma process, issuing an alert, suspendingexecution of any further plasma processes in the chamber until it isappropriately cleaned, or any combination thereof.

Various features may be utilized by the fourteenth aspect of the presentinvention, and these features may be used alone in relation to thisfourteenth aspect as well as in any combination. The data which isobtained on the current plasma process may be optical emissions of theplasma in the chamber. Wavelengths obtained may include at least fromabout 250 nanometers to about 1,000 nanometers which defines a firstwavelength range. Data may be obtained at least at every 1 nanometerthroughout the noted first wavelength range.

Numerous techniques may be implemented to determine if the processingchamber should be cleaned using the data obtained on the plasma in thechamber. Description of these techniques will be in relation to opticalemissions data. The current optical emissions (from the current time inthe process) may be compared with a standard which is stored on acomputer-readable storage medium. This standard may be optical emissionsof plasma from the same chamber, but from a plasma process previouslyrun in the chamber where the chamber was determined or assumed to be inneed of cleaning. When the current optical emissions are at leastsubstantially a match with this standard, the chamber will be deemed tobe in need of cleaning. "Matches" may be based upon any patternrecognition technique. Determining the differential between the currentoptical emissions and the standard may also be used for this purpose.

Another way of determining when to clean the chamber using data obtainedon the plasma involves endpoint detection. Each of the endpointdetection techniques discussed above in relation to the tenth throughthe thirteenth aspects of the present invention use data relating to theplasma in the chamber to identify endpoint. When any step of a multiplestep plasma process takes longer than a pre-set maximum time limit, thechamber may be deemed to be in need of cleaning. If the total time tocomplete an entire plasma process takes longer than a pre-set maximumtime limit, the chamber may also be deemed to be in need of cleaning.Endpoint detection techniques may be used in each of these cases. In thecase of a multiple step plasma process, the endpoint may be identifiedfor each of the steps of a multiple step process, or simply the endpointof the last step in the subject plasma process may be identified, todetermine the total time spent on the process.

Plasma cleaning operations are embodied within a fifteenth aspect of thepresent invention. A plasma clean removes materials from the interior ofthe processing chamber by having plasma exist within an "empty" chamber.No product (e.g., wafers) is contained within the chamber during aplasma clean.

Optical emissions of the plasma in the "empty" chamber are obtained at aplurality of times during the process in a first embodiment of thisfifteenth aspect. A pattern of at least a portion of the opticalemissions is compared with a first standard pattern during at least aportion of the process (e.g., a plot of intensity versus time). Thisfirst standard pattern may be recorded on a computer-readable storagemedium. Furthermore, this first standard pattern may be from opticalemissions of plasma in a plasma process previously conducted within thesame processing chamber at a time when the plasma clean had reached itsendpoint. When the pattern of optical emissions from at least one timeduring the process and the first standard pattern are within apredetermined amount of each other, the plasma process is terminated."Predetermined amount" contemplates using pattern recognitiontechniques, as well as taking a differential and noting when thisdifferential is at least substantially free from any substantialintensity peaks.

Various features may be utilized by the first embodiment of thefifteenth aspect of the present invention, and these features may beused alone in relation to this fifteenth aspect as well as in anycombination. Wavelengths including at least those from about 250nanometers to about 1,000 nanometers (first wavelength range), at leastat every 1 nanometer throughout the first wavelength range, may beobtained and utilized for the comparison with the first standardpattern. All of these optical emissions may be utilized, or only aportion thereof. That is, the first embodiment of this fifteenth aspectincludes comparing the pattern of a specific wavelength(s) within theoptical emissions of the plasma with the first standard pattern whichwill include the corresponding wavelength(s). Moreover, the firstembodiment also includes comparing the pattern of the entirety of theoptical emissions obtained on the current plasma process with the firststandard pattern.

Difficulties may be encountered when using a particular wavelength forthe first standard pattern. One such difficulty may be finding thisparticular wavelength in the optical emissions of the current plasmaprocess due, for instance, to a wavelength shift. Additional featuresmay be utilized in the first embodiment of the fifteenth aspect toaddress this type of a situation. In this regard, the first standardpattern may be part of a first standard optical emissions segment whichincludes a plurality of wavelengths. The intensity peak associated withthe subject wavelength of the first standard pattern may be identifiedin relation to its intensity (e.g., it is the "largest" intensity peakaround a certain wavelength), one or more other intensity peaks (e.g.,the subject wavelength is the "middle" peak in a certain wavelengthregion), or both. Noting these characteristics of the wavelength for thefirst standard pattern in the first standard optical emissions segmentmay then be used to identify the subject wavelength in the currentoptical emissions segment.

The first embodiment of the subject fifteenth aspect may also beterminated if the subject plasma process has reached a predeterminedmaximum time limit before the current pattern and first standard patternare within a predetermined amount of each other. Typically this willmean that the current plasma process was ineffective in addressing theinterior of the processing chamber. In this type of a case, a wet cleanof the chamber may be initiated. Thereafter, another plasma cleaningoperation may be initiated to address the residuals of the wet clean.

Monitoring the time rate of change of optical emissions of the plasma inthe chamber is the subject of a second embodiment of the fifteenthaspect relating to plasma cleans. In this regard, the differentialbetween the optical emissions at a current time in the process and theoptical emissions from a previous time in the same plasma process(preferably an immediately preceding time) is determined. When thisdifferential is no more than a first amount, the current plasma processis terminated. Therefore, this second embodiment equates the time atwhich the plasma clean should be terminated with a situation where thecurrent plasma process is no longer changing the condition of theinterior of the processing chamber at a desired rate. All or a portionof those "additional" features addressed above in relation to the firstembodiment may be implemented in this second embodiment as well.

Conditioning wafer operations are addressed in a sixteenth aspect of thepresent invention. At least one conditioning wafer is loaded in aprocessing chamber and a plasma process is run thereon. Typically theplasma process will etch a pattern on the conditioning wafer which issomething other than an integrated circuit or a pattern which would notbe associated with a semiconductor device. Plasma processing of theconditioning wafer is monitored through obtaining optical emissions ofthe plasma in the chamber. A number of conditioning wafers are processedin this manner until the conditioning wafer operation is terminatedbased upon the results of the monitoring of one of the plasma processesconducted on a conditioning wafer. Thereafter, a production waferoperation is initiated whereby at least one production wafer is loadedin the chamber and a plasma recipe (e.g., one or more plasma steps) isrun thereon. These production wafers are removed from the chamber and atleast one semiconductor device is formed therefrom. Further processingof the production wafer may be required before the actual semiconductordevice is available. Therefore, this distinguishes a production waferfrom a conditioning wafer since no semiconductor devices are formed fromconditioning wafers. Instead, conditioning wafers are either typicallyscrapped or refurbished for further use as a conditioning wafer.

Various features may be utilized by the sixteenth aspect of the presentinvention, and these features may be used alone in relation to thissixteenth aspect as well as in any combination. The health of theconditioning wafer operation, the health of the production waferoperation, or both may be evaluated. Any of the techniques discussedabove in relation to the seventh and tenth aspects of the inventionthereby may be implemented in this sixteenth aspect as well. Opticalemissions obtained on the conditioning wafer operation, the productionwafer operation, or both may include at least wavelengths from about 250nanometers to about 1,000 nanometers, and such optical emissions may beobtained at least at every 1 nanometer throughout this range. All or aportion of this data may be utilized in a comparison upon whichtermination of the conditioning wafer operation is based.

Endpoint detection techniques may be used to terminate the conditioningwafer operation. Therefore, any of the endpoint detection techniquesdiscussed above in relation to the ninth through the thirteenth aspectsmay be implemented in this sixteenth aspect as well. Termination of theconditioning wafer operation may also be based upon when consecutiverunnings of the plasma process on conditioning wafers are within acertain amount of each other as determined through the data obtained onthe process. That is, the termination of the conditioning waferoperation may be equated with the conditioning wafer operation havingreached a steady state (e.g., the processing of one conditioning waferlooks at least effectively the same as the processing of the nextconditioning wafer) determined in accordance with an evaluation ofoptical emissions data. Termination of the conditioning wafer operationmay also be based solely on the data obtained on the conditioning waferoperation. That is, no wafer need be analyzed before the productionwafer operation is initiated. One or more of a plasma cleaningoperation, a wet cleaning operation, or a replacement of consumables mayalso be initiated before the initiation of the conditioning waferoperation as well.

Management of the distribution of wafers to a wafer production systemincluding at least two processing chambers is addressed by a seventeenthaspect of the present invention. In a first embodiment, at least twochambers are involved in the plasma processing of wafers disposedtherein. Each plasma process conducted within these chambers ismonitored in at least some respect. Wafers will continue to besequentially processed in these chambers unless the monitoring of thecurrent plasma process on the wafer(s) in one of these chambers detectsthe existence of one or more conditions. These conditions include theexistence of a "dirty chamber", a known error condition, an unknowncondition, or a combination thereof as these terms have been used inrelation to the sixth and fourteenth aspects discussed above. Thedistribution of wafers to this particular chamber may be suspendedimmediately after this type of condition is identified, or suspensionmay be delayed until a certain number of these types of conditions areencountered in multiple plasma processes. That is, a given chamber maynot be taken "off line" until this same condition (or another of theconditions) have been identified in multiple runs.

When the suspension of processing of wafers in a given chamber is basedupon the identification of a "dirty chamber" condition, the chamber maybe cleaned in some manner. Plasma cleans, wet cleans, replacement ofconsumables, or any combination thereof are contemplated as anappropriate "cleaning" in the context of this first embodiment of theseventeenth aspect. Once the chamber has been cleaned, the distributionof wafers for running plasma processes thereon may be reinitiated.Encountering a known error during the plasma processing of a wafer(s) inone of the chambers may result in the modification of one or moreprocess control parameters to address this error. Finally, when anunknown condition is encountered, the first embodiment contemplatesanalyzing the plasma process after termination thereof in an attempt toidentify the corresponding cause.

A second embodiment of the seventeenth aspect relates to the running ofplasma processes on product in at least three chambers. The wafers aredistributed to these chambers using a first sequence. Modification ofthis sequence is initiated if the monitoring of the plasma process inone of the chambers identifies the existence of a certain condition. Anyof those identified above in relation to the first embodiment would beapplicable to this second embodiment as well. In this regard, thecorresponding features from the first embodiment may be implemented inthis second embodiment as well.

Finally, a third embodiment of this seventeenth aspect involves thedistribution of wafers to at least two processing chambers for therunning of a plasma process thereon. The time required to complete eachplasma process is monitored. The distribution sequence which is utilizedis based upon this monitoring of time. For instance, the distributionsequence may involve maximizing the use of the "fastest" processingchamber.

The present invention will now be described in relation to theaccompanying drawings which assist in illustrating its various pertinentfeatures. One application of the present invention is for processeswhich utilize plasma to provide at least one function or to achieve atleast one predetermined result, and the present invention will hereafterbe described in this context. More specifically, the present inventionwill be described in relation to the running of plasma processes onwafers or the like from which semiconductor devices are formed (e.g.,etching where the "predetermined result" may be the removal of one ormore layers, chemical vapor deposition where the predetermined resultmay be the buildup of one or more films, sputtering where thepredetermined result may be the addition or removal of material).

Wafer Production System 2--FIG. 1

A wafer production system 2 is illustrated in FIG. 1 and is generallyfor executing one or more plasma-based processes (single or multiplestep) on wafers 18. Semiconductor devices may be formed from wafers 18processed by the system 2, including integrated circuit chips. Thesystem 2 generally includes a wafer cassette 6 which stores a pluralityof wafers 18 and allows these wafers 18 to be readily transported to andfrom the system 2. One wafer cassette 6 is disposed in each of the twoload lock chambers 28 of the wafer production system 2. A wafer handlingassembly 44 is advanced into the respective load lock chamber 28,removes at least one of the wafers 18 from the wafer cassette 6, andtransfers the wafer(s) 18 to one of the plurality of processing chambers36 of the wafer production system 2 (four chambers 36a-d beingillustrated). Other arrangements may be utilized for purposes of thepresent invention.

Control of the wafer handling assembly 44, as well as various othercomponents of the wafer production system 2, is provided by a maincontrol unit 58 (hereafter "MCU 58"). In one embodiment, the MCU 58 is acomputer having at least one computer-readable storage medium and atleast one processor, such as a desktop PC or a main-frame havingsatellite terminals. Appropriately integrating the MCU 58 with one ormore other components of the wafer production system 2 allows the MCU 58to be the main controller for the chamber 36. Integration may includeoperatively interfacing the MCU 58 with these various components andincluding the wafer handling assembly 44. Other hardware may also beoperatively interconnected with the MCU 58, such as a display 59 forproviding visual-based information to operations personnel (e.g., a CRTor computer monitor), as well as a data entry device 60 (e.g., mouse,light pen, keyboard) for allowing operations personnel to enterinformation used by or relating to the wafer production system 2.

Plasma within the chambers 36 processes the enclosed wafer(s) 18 in somemanner (e.g., etching to remove a predetermined layer of material). Atransparent window 38 is provided on each chamber 36 to allow opticalemissions data to be obtained on the plasma recipe being run on thewafer(s) 18 in the respective chamber 36. Once the plasma process iscompleted, the wafer handling assembly 44 removes the wafer(s) 18 fromthe respective processing chamber 36 and transfers the wafer(s) 18 backto one of the wafer cassettes 6 in the associated load lock chamber 28.When all of the wafers 18 within one of the cassettes 6 have been plasmaprocessed, the wafer cassette 6 is removed from the load lock chamber 28and replaced with another cassette 6 with new wafers 18 to be plasmaprocessed. This may be done manually by operations personnel or in anautomated manner by robots or the like.

Wafer Cassette 6--FIG. 2

More details regarding the embodiment of the wafer cassette 6 which isincorporated in the wafer production system 2 of FIG. 1 are presented inFIG. 2. The wafer cassette 6 includes a frame 10 defined by a pair oflaterally spaced sidewalls 22 which are interconnected by a back panel26, as well as a pair of end panels 8. The front of the frame 10 issubstantially open such that the wafer handling assembly 44 may beadvanced within and retracted from the wafer cassette 6 to remove wafers18 from and provide wafers 18 to the associated wafer cassette 6. Aplurality of longitudinally spaced and laterally disposed partitions 16(e.g., each partition 16 being disposed at least generally perpendicularto the longitudinal axis of the cassette 6) are provided within theframe 10 for purposes of maintaining separation of adjacent wafers 18.Each pair of adjacent partitions 16 defines a pocket 14 in which asingle wafer 18 may be placed. Loading of wafers 18 within the wafercassette 6 which are to be plasma processed may be accomplished bydisposing the one of the end panels 8 of the cassette 6 on anappropriate supporting surface and manually loading wafers 18 into thecassette 6, with only one wafer 18 being disposed in any of the pockets14. Once the wafer cassette 6 is loaded with wafers 18 to the desireddegree, the cassette 6 may be transported to the appropriate load lockchamber 28. The wafer cassette 6 is then disposed on one of its ends 8in a position such that its substantially open front faces and isaccessible by the wafer handling assembly 44. Other configurations forwafer cassettes 6 may be utilized by the wafer production system 2, andautomation may be implemented in any one or more of the loading ofwafers 18 into the cassette 6 and the transport of the cassette 6 to andfrom the load lock chambers 28 of the wafer production system 2.

Wafer Handling Assembly 44--FIGS. 3A-3B

Additional details regarding the wafer handling assembly 44 which isincorporated in the wafer production system 2 of FIG. 1 are illustratedin FIGS. 3A-B. Other types of wafer handling assemblies may be utilizedby the wafer production system 2, such as the types disclosed in U.S.Pat. No. 5,280,983 to Maydan et al., issued Jan. 25, 1994, and entitled"SEMICONDUCTOR PROCESSING SYSTEM WITH ROBOTIC AUTOLOADER AND LOCK" andU.S. Pat. No. 5,656,902 to Lowrance, issued Aug. 12, 1997, and entitled"TWO-AXIS MAGNETICALLY COUPLED ROBOT", both of which patents areincorporated by reference in their entirety herein. The wafer handlingassembly 44 of FIGS. 3A-B generally includes a robotic wafer handler 48which is disposed within a central chamber 70 of the wafer productionsystem 2. Load lock chambers 28 and processing chambers 36 are therebydisposed about the wafer handling assembly 44. Movement of the roboticwafer handler 48 is realized through a wafer handler control motor 62which is operatively interfaced with the wafer handier 48, and which inturn is operatively interfaced with and controlled by the MCU 58 (FIG.1). The wafer handler 48 includes a pivot 50 such that the wafer handler48 may be pivoted or rotated about the pivot 50 to position the waferhandling assembly 44 to appropriately interface with one of the loadlock chambers 28 or processing chambers 36. Wafers 18 are removed fromand provided to the respective load lock chamber 28 or processingchamber 36 by a wafer blade 66 which interfaces with one of the wafers18 when disposed in one of the pockets 14 of the wafer cassette 6. Avacuum chuck or the like may be incorporated on the wafer blade 66 toretain the wafer 18 on the blade 66 (not shown). The wafer blade 66 isinterconnected with an arm assembly 54 which extends and retracts viapivotal-like action to axially advance and retract the wafer blade 66 tothe appropriate position.

Processing Chamber 72--FIGS. 4 and 5

One embodiment of a processing chamber which may be incorporated in thewafer production system of FIG. 1 as one of the chambers 36 is presentedin more detail in FIG. 4. Other types/configurations of processingchambers may be utilized by the wafer production system 2 for purposesof the present invention as well, including those disclosed in U.S. Pat.No. 5,614,055 to Fairbairn et al., issued Mar. 25, 1997, and entitled"HIGH DENSITY PLASMA CVD AND ETCHING REACTOR", and U.S. Pat. No.5,641,375 to Nitescu et al., issued Jun. 24, 1997, and entitled "PLASMAETCHING REACTOR WITH SURFACE PROTECTION MEANS AGAINST EROSION OF WALLS",both patents of which are incorporated by reference in their entiretyherein.

The processing chamber 74 of FIG. 4 is specifically adapted forperforming a plasma etching operation on a wafer(s) 18 when disposedtherein (i.e., to remove one or more layers from the wafer(s) 18disposed in the chamber 36). The processing chamber 74 includes chambersidewalls 78 which are disposed about a central, longitudinal axis 76 ofthe chamber 74. Access to the processing chamber 74 may be provided by achamber cover 82 which is interconnected with the chamber sidewalls 78in such a manner that at least in certain instances, at least a portionof the chamber cover 82 may be moved away from the chamber sidewalls 78.In the illustrated embodiment, the chamber cover 82 is removed only togain access to the interior of the processing chamber 74 formaintenance, cleaning, or both. A window port 124 extends through aportion of the chamber sidewall 78 and is aligned with a transparentwindow 112. The window 112 includes an inner surface 116 and an outersurface 120, and provides a way for the plasma to be viewed exteriorlyof the processing chamber 74 and further to provide a mechanism forobtaining optical emissions data on the plasma recipe being run on thewafer(s) 18 within the chamber 74.

Protection of the chamber sidewalls 78 and the chamber cover 82 from theeffects of plasma processes being conducted within the chamber 74 isprovided by a bell jar 90 and a bell roof 86 which are each formed fromtransparent, dielectric materials (e.g., quartz, sapphire). The bell jar90 is spaced radially inward (e.g., in the direction of the central,longitudinal axis 76 of the chamber 74) from the inner surface of thechamber sidewalls 78. The bell roof 86 is disposed above the bell jar 90and is axially movable in a direction which is at least substantiallyparallel with the central, longitudinal axis 76 of the chamber 74through interconnection with an elevator 98. Movement of the elevator 98may be desirable for one or more purposes. For instance, this movementmay be used to change the spacing between a showerhead 94 and a waferpedestal 106/wafer platform 102 which in one embodiment are theelectrodes or "plasma generator" for the chamber 74.

The wafer pedestal 106 is disposed radially inwardly of the bell jar 90in spaced relation therewith, and the wafer platform 104 is disposed ontop of the wafer pedestal 106. In one embodiment, both the waferpedestal 104 and wafer platform 106 are formed from silicon-basedmaterials since the wafers 18 are also commonly formed fromsilicon-based materials. The wafer 18 is introduced into the processingchamber 74 through a wafer access 80 which extends through the chambersidewall 78, and is disposed in a flat orientation on the upper surfaceof the wafer platform 104. Various mechanisms may be used to retain thewafer 18 on the wafer platform 104 during the running of the plasmaprocess on the wafer 18 in the chamber 74, such as by drawing a vacuumthrough a vacuum port 108 which is formed on the wafer platform 104 orby using electrostatic charges (not shown). Transport of the wafer 18into the processing chamber 74 is again provided by the wafer blade 66of the wafer handling assembly 44 (FIGS. 1 and 3A-B). After the waferblade 66 is retracted from the processing chamber 74, a vacuum isgenerated within the processing chamber 74 before the plasma process isinitiated.

The showerhead 94 is interconnected with the elevator 98 such that it isaxially movable therewith, and in one embodiment is also formed from asilicon-based material for the above-noted reasoning. The showerhead 94includes one or more apertures (not shown) for the purpose of dispersingfeed gases within the vacuum chamber 84 in a manner to define a desiredgas flow pattern for the plasma. Gases are provided to the showerhead 94through a gas inlet port 100 formed in the quartz bell roof 86. Withappropriate gases being contained within the processing chamber 74 andunder other appropriate conditions (e.g., pressure, temperature, flowrate), an appropriate voltage may be applied to one or more of the waferpedestal 106 and the showerhead 94 to create the plasma within thechamber 74 above the wafer platform 104. The wafer pedestal 106 andwafer platform 104, as well as the showerhead 94, thereby also functionas electrodes in the illustrated embodiment as noted. The electricalfield generated by these electrodes also functions to effectivelyconfine the plasma to the space between the electrodes.

FIG. 5 illustrates one embodiment of a gas delivery system 150 which maybe used to provide gases to the processing chamber 74 of FIG. 4 for agiven plasma process operation. Other systems may be utilized as well.The gas delivery system 150 includes a plurality of storage tanks 154,each of which is fluidly interconnected with the processing chamber 74either directly or indirectly. Storage tanks 154b-d are available forcontaining one or more types of feed gases which will define the gascomposition of the plasma within the vacuum chamber 84. Each storagetank 154b-d is fluidly interconnected with a mixer 166 by gas lines158b-d where the feed gases may be appropriately mixed prior to beingprovided to the processing chamber 74 through the showerhead 94 via thegas line 158e. Mixing of the feed gases could also occur in a manifold(not shown) into which each of the feed gases would separately flow andwhich could be contained within or be part of the processing chamber 74.The manifold would then interface with the gas inlet port 100, and thistype of manifold may also be used in combination with the mixer 166. Insome cases the composition of the feed gases provided to the processingchamber 74 to define the plasma may be difficult to ignite. Thissituation is remedied by including an appropriate gas in the storagetank 154a. A gas composition which is more readily ignitable than thecomposition of the feed gases is contained within the storage tank 154a.Ignition of the plasma would then be affected by directing a flow of theignition gas from the storage tank 154a into the processing chamber 74,along with a flow of the desired feed gases from the storage tanks154b-d, and using the ignition of the ignition gas to then ignite thefeed gases to generate the plasma.

Plasma Monitoring Assembly 174--FIGS. 6 and 7

The above-described components are obviously important to the overallfunction of the wafer production system 2. However, the presentinvention is more specifically directed to the monitoring or evaluationof the plasma itself. Therefore, the following components may beincorporated in any type of plasma-based system, including theforegoing.

One embodiment of an assembly for monitoring/evaluating plasma processesand which may be incorporated in the wafer production system 2 of FIG. 1is illustrated in FIG. 6. The plasma monitoring assembly 174 operativelyinterfaces with the window 38 of the processing chamber 36 by receivingoptical emissions of the plasma which pass out of the processing chamber36 through the window 38. These optical emissions are "collected" by anappropriate fiber optic cable 178 which is positioned at or near theouter surface 42 of the window 38. Fixtures which illustrate ways ofmaintaining a fiber optic cable and a window of a processing chamber ina fixed positional relationship are presented in FIGS. 36 and 39.Optical emissions of the plasma within the processing chamber 36 duringprocessing of a wafer 18 enter the fiber optic cable 178 and aredirected to a spectrometer assembly 182. Both scanning-type and solidstate spectrometers may be used as the spectrometer assembly 182. Theassembly 182 may also include one or more appropriately interconnectedspectrometers, each of which obtains optical emissions data from adifferent region. The spectrometer assembly 182 separates these opticalemissions into a plurality of individual wavelengths and provides theseseparate optical components to an array 186 of charge coupled devices(hereafter "CCD array 186") for conversion to a corresponding electricalsignal.

A computer-readable signal is provided by the CCD array 186 to a plasmamonitor control unit 128 (hereafter "PMCU 128") which is the primarycontrol mechanism of the plasma monitoring assembly 174. In oneembodiment, the PMCU 128 is a computer which may be configured toinclude, but not limited to, at least one motherboard, at least oneanalog-to-digital conversion board, at least one central processing unit(CPU) for each motherboard, and one or more types of computer-readablestorage mediums such as at least one floppy disk drive, at least onehard disk drive, and at least one CD ROM drive. Other hardware may beoperatively interconnected with the PMCU 128, such as a display 130 forproviding visual/audio-based information to operations personnel (e.g.,a CRT, LCD, or computer monitor), as well as one or more data entrydevices 132 (e.g., mouse, light pen, keyboard) for allowing personnel toenter information used by or relating to the plasma monitoring assembly174. One PMCU 128 may be provided for each chamber 36, or the PMCU 128may be configured to service multiple chambers 36. The PMCU 128 is alsooperatively interfaced or interconnected with the MCU 58 of the waferproduction system 2 such that the PMCU and MCU 58 may communicate witheach other.

The PMCU 128 includes a plasma monitoring module 200 and each of itssub-modules may be stored on a computer-readable storage mediumassociated with the PMCU 128 (e.g., on a portable computer diskette(s),on a hard drive, on a CD(s)). The plasma monitoring module 200 and thesesub-modules are illustrated in FIG. 7. One sub-module is a startupmodule 202 which provides a way of accessing other sub-modules through acurrent plasma process module 250. The current plasma process module 250of the plasma monitoring module 200 facilitates the monitoring orevaluation of the various types of plasma processes which may beconducted within the chamber 36 through the evaluation of opticalemissions data of the plasma in the chamber 36. In the case of the FIG.6 embodiment, optical emissions data are collected and delivered by thefiber optic cable 178 to the spectrometer assembly 182 which divides thelight up into its individual optical components. Data representative ofthese optical emission components are then made available to the currentplasma process module 250 through the CCD array 186 as described above.

Evaluation or monitoring of the current plasma process through thecurrent plasma process module 250 is facilitated by collecting opticalemissions from the plasma preferably to include at least wavelengthsfrom within the UV range to within the near infrared range, and therebyincluding the visible light spectrum. In one embodiment, opticalemissions of the plasma in the processing chamber 36 which are obtainedand available for evaluation (e.g., by the current plasma process module250, manually by the appropriate personnel) include at least thosewavelengths from about 250 nanometers to about 1,000 nanometers(inclusive), and more preferably at least those wavelengths from about150 nanometers to about 1,200 nanometers (inclusive). Hereafter theabove-noted desired range or bandwidth of optical emissions data whichare obtained/collected of the plasma in the chamber 36, and whichincludes each of the above-noted ranges or bandwidths, will be referredto as the "Preferred Optical Bandwidth."

Optical or wavelength resolutions within and throughout the PreferredOptical Bandwidth are preferably no more than about 1 nanometer, andeven more preferably no more than about 0.5 nanometers (presentlycontemplating a wavelength resolution of 0.4). The term "wavelengthresolution" in this context means the amount of separation betweenadjacent wavelengths in the subject optical emissions data which iscollected. Therefore, if the wavelength resolution being used to collectoptical emissions data from the plasma in the chamber 36 is 1 nanometer,no more than a 1 nanometer spacing will exist between any two datapoints within and throughout the Preferred Optical Bandwidth. Althoughequal spacings will typically be utilized in relation to the wavelengthresolution within and throughout the Preferred Optical Bandwidth, thisneed not be the case such that "wavelength resolution" encompasses equalspacings, unequal spacings, and combinations thereof. Hereafter, theabove-noted magnitude for the optical or wavelength resolution will bereferred to as the "Preferred Data Resolution."

Another factor relating to the effectiveness of the current plasmaprocess module 250 in relation to the amount of optical emissions dataof the plasma in the chamber 36 is the times at which this data is takenduring the subject plasma process. Optical emissions data of the plasmain the chamber 36 are preferably obtained at least every 1 second, andmore preferably at least every 1/3 second. Although equal spacings willtypically be utilized in relation to the times at which opticalemissions data is collected on the plasma in the chamber 36, this neednot be the case such that equal time spacings, unequal spacings, andcombinations thereof may be utilized. Hereafter, the above-noted timingmagnitudes for obtaining optical emissions data of the plasma in thechamber 36 will be referred to as the "Preferred Data Collection TimeResolution."

The spectrometer assembly 182 illustrated in FIG. 6 should be capable ofmeeting the above-noted criteria, and a number of implementations may beutilized. For instance, the spectrometer assembly 182 may be of thescanning type in which the spectrometer assembly 182 would includestructure to scan the spectrum to obtain data encompassing the PreferredOptical Bandwidth using the Preferred Data Resolution and at thePreferred Data Collection Time Resolution (e.g., scan a first opticalemissions segment or region of the 250-550 nanometer wavelengths, scan asecond segment of the 500-750 nanometer wavelengths, and scan a thirdsegment of the 700-950 nanometer wavelengths, each of which overlaps sothat the possibility of losing data is reduced and further to facilitatealignment of spectral segments). The spectrometer assembly 182 may alsobe a solid state device. Multiple subunits or processing cards may beconnected in parallel relation to function similar to the scanning typenoted above. That is, each subunit or processing card of the solid statedevice would then provide information on a specific optical emissionssegment or region within the Preferred Optical Bandwidth using thePreferred Data Resolution and at the Preferred Data Collection TimeResolution.

Exemplary Plasma Recipe Spectra--FIG. 8

A representative or exemplary spectra in computer-readable form whichmay be made available to the current plasma process module 200 of FIG. 7for analysis is presented in FIG. 8. Only a portion of the PreferredOptical Bandwidth is represented by the spectra 246. However, it servesto illustrate certain principles associated with the present inventionsince the evaluation of the current plasma process need not be of theentire Preferred Optical Bandwidth in each case. The spectra 246contains data within the wavelength range of 400 nanometers to about 700nanometers and at a certain fixed point in time in a plasma processbeing conducted within the processing chamber 36 of FIG. 1 (e.g., at acurrent time t_(n)). Various characteristics of the spectra 246 of FIG.8 may be used in the analysis undertaken by the current plasma processmodule 250 of FIG. 7. These characteristics include the overall patternof the spectra 246, one or more of the location and intensity of one ormore of intensity peaks 248 in the spectra 246, and one or more of therelative location and relative intensity of one or more of the intensitypeaks 248.

The current plasma process module 250 of FIG. 7 operatively interfaceswith a collection of spectra obtained from one or more plasma processespreviously conducted within the subject processing chamber 36.Generally, the current plasma process module 250 receives data from thecurrent plasma process being conducted within the plasma processingchamber 36, and in all but one case (the research module 1300) comparesthis data or at least a portion thereof with data from one or moreplasma processes previously conducted within this very same plasmaprocessing chamber 36 to evaluate or monitor the current plasma process.This comparison provides certain information regarding the currentplasma process depending upon which sub-module(s) of the current plasmaprocess module 250 is being utilized. Each of these sub-modules will bediscussed in more detail below in relation to the relevant figures.However, understanding how the data is organized for access by thecurrent plasma process module 250 may facilitate a more completeunderstanding of these sub-modules.

Plasma Spectra Directory 284--FIGS. 9-12B

One embodiment of how the collection of data on prior plasma processesmay be organized for use by the current plasma process module 250 isillustrated in FIG. 9. The plasma spectra directory 284 of FIG. 9includes a number of subdirectories or subsets of categorically similardata, is typically specific to a single processing chamber 36 (althoughthe same directory 284 could be used for multiple chambers 36 if thedata within the directory 284 was indexed in some way to the specificchamber 36), is accessed by one or more of the submodules of the currentplasma process module 250, and is preferably stored in acomputer-readable medium of or associated with the PMCU (e.g., one ormore computer diskettes, hard drive, one or more CDs). Relevant datawhich is included in each data entry in each of these subdirectories ofthe plasma spectra directory 284 is a spectra (optical emissions data),and in all but one case (spectra of calibration light subdirectory 310)is a spectra of the plasma in the processing chamber 36 at the relevanttime and typically within the Preferred Optical Bandwidth and at thePreferred Data Resolution unless otherwise noted herein.

Plasma processes which are to be used as a standard of sorts forevaluating/monitoring plasma processes currently being run in theprocessing chamber 36, or to assess the health or condition of theplasma during such plasma processes, are stored in a subdirectory of theplasma spectra directory 284 of FIG. 9 which is entitled the "Spectra of"Normal" Plasma Processes" and identified by reference numeral 288(hereafter "normal spectra subdirectory 288"). Actual spectral data fromone or more plasma processes which have been conducted in the processingchamber 36 are stored in the normal spectra subdirectory 288 associatedwith this chamber 36. Various categories or genera of plasma processesmay be stored in the normal spectra subdirectory 288, such as theabove-noted plasma recipes, plasma cleaning operations or plasma cleans(with or without previously conducting a wet clean), and conditioningwafer operations, and one or more executions of plasma processes withineach of these categories may also be stored in the subdirectory 288.Each category of plasma process may be organized in a "folder" or thelike of the normal spectra subdirectory 288, or may have a code whichidentifies it as being representative of a particular category/genus ofplasma process to group categorically similar processes together (e.g, afolder for "normal" plasma recipes, a separate folder for "normal"plasma cleans which are run without first wet cleaning the chamber 36, aseparate folder for "normal" plasma cleans which are run after a wetclean of the chamber 36, and a separate folder for "normal" conditioningwafer operations).

Spectral data is used by the current plasma process module 250 todetermine if subsequent plasma processes conducted in this very sameprocessing chamber 36 are proceeding in accordance with at least one ofthe plasma processes stored in the normal spectra subdirectory 288.Entries in the normal spectra subdirectory 288 are thereby used as a"model" or "standard" for the evaluation of plasma processes conductedin this very same processing chamber 36 at some future time. How data isactually entered in the normal spectra subdirectory 288 will bediscussed in more detail below in relation to the startup module 202 andFIGS. 13-14. Suffice it to say for present purposes that entries in thenormal spectra subdirectory 288 are from actual plasma processesconducted in the subject chamber 36. These plasma processes are eitherconfirmed (e.g., by post-plasma processing testing) or assumed (andtypically later confirmed) to have proceeded in a desired orpredetermined manner, or more specifically without anysubstantial/significant errors or aberrations. No pre-analysis orknowledge of any plasma process is required to use the current plasmaprocess module 250 and the normal spectra subdirectory 288 to evaluate aplasma process currently being conducted in the processing chamber 36.Spectral data from a plasma process ABC conducted in a given chamber 36may be recorded in the normal spectra subdirectory 288 one day simplyfor purposes of determining if any subsequent running of this sameplasma process ABC in this same chamber 36 has proceeded in accordancewith the spectral data from the plasma process ABC previously recordedin the normal spectra subdirectory 288.

Errors or aberrations which have been previously encountered whilerunning a plasma process in the processing chamber 36 are containedwithin a subdirectory of the plasma spectra directory 284 of FIG. 9which is entitled "Spectra of "Abnormal" Plasma Processes" andidentified by reference numeral 292 (hereafter "abnormal spectrasubdirectory 292"). Data relating to any of the plasma processesreferenced above in relation to the normal spectra subdirectory 288 mayalso be stored in the abnormal spectra subdirectory 292, and theabove-noted organizational techniques may be utilized here as well.Entries to the abnormal spectra subdirectory 292 are made when a givenplasma process conducted in the processing chamber 36 does not proceedin the desired or predetermined manner (e.g., when the process has notproceeded according to the relevant plasma process(es) of the normalspectra subdirectory 288), and further when the cause or causes of theerror or aberration has been identified to the plasma spectra directory284. This typically requires analysis of at least that portion of thespectral data from the time when the error or aberration in the subjectplasma process first occurred, as well as possibly spectral data fromthe remainder of the subject plasma process. Errors or aberrations in aplasma process will typically be evident in the spectra of the plasma inthe processing chamber 36. Moreover, by obtaining data on the currentplasma process in the Preferred Optical Bandwidth, at the Preferred DataResolution, and at the Preferred Data Collection Time Resolution, thechances of obtaining optical emissions data which is indicative of thesubject error or aberration is enhanced.

When spectral data on a current plasma process being conducted in theprocessing chamber 36 deviates from the corresponding spectral data inthe normal spectra subdirectory 288 in the determination of the currentplasma process module 250, the module 250 may then compare this"deviating spectral data" on the current plasma process with spectraldata in the abnormal spectra subdirectory 292. Any number of actions maybe initiated if the current plasma process module 250 identifies a"match" between the spectral data from the plasma process currentlybeing conducted in the processing chamber 36 and spectral data in theabnormal spectra subdirectory 292. These actions may include issuing anappropriate alert(s) of the error condition, addressing one or moreaspects of or relating to the control of the chamber 36, or both as willbe discussed in more detail below in relation to the process alertmodule 428 of FIG. 14.

Spectral data from a plasma process which is currently being conductedin the subject processing chamber 36, which does not "match" any plasmaprocess stored within the normal spectra subdirectory 288, and whichfurther does not "match" with corresponding spectral data in theabnormal spectra subdirectory 292, is recorded in a subdirectory of theplasma spectra directory 284 which is entitled "Spectra of "Unknown"Plasma Processes" and identified by reference numeral 296 (hereafter"unknown spectra subdirectory 296"). There are a number of circumstanceswhen data from a plasma process which is being currently conducted inthe processing chamber 36 will be recorded in the unknown spectrasubdirectory 296. Any error or aberration which is "new" to the currentplasma process module 250 (i.e., spectral data, indicative of an erroror aberration, which has not been previously recorded in the abnormalspectra subdirectory 292) will result in relevant data from the currentplasma process being recorded in the unknown spectra subdirectory 296.Another circumstance where data may be entered in the unknown spectrasubdirectory 296 is when the current plasma process being conducted inthe processing chamber 36 is actually a new plasma process in relationto the current plasma process module 250. That is, the subject plasmaprocess may very well be proceeding in accordance with the desired orpredetermined manner, but data on this particular plasma process has nothave been previously recorded in the normal spectra subdirectory 288 ofFIG. 9. As such, the spectral data of the current plasma process wouldnot match any plasma process in the normal spectra subdirectory 288, andshould not match any corresponding spectral data in the abnormal spectrasubdirectory 292. When an "unknown" condition is encountered duringoperations, an appropriate alert may be issued, control of the currentprocess may be addressed, or both.

Spectral data recorded in the unknown spectra subdirectory 296 fromprior plasma processes will typically be analyzed by personnel at somepoint in time after the process has been terminated. If the spectraldata from a plasma process recorded in the unknown spectra subdirectory296 is identified as being a new plasma process, and if a determinationis made to use this spectral data as a standard for evaluating furtherrunnings of this same plasma process on this same processing chamber 36,this spectral data may be transferred to the normal spectra subdirectory292. Entries may also be made to the abnormal spectra subdirectory 292from the unknown spectra subdirectory 296. Analysis of the spectral datafrom a particular plasma process which is recorded in the unknownspectra subdirectory 296 may lead to the conclusion that the spectraldata is associated with one or more particular errors/aberrations whichis identifiable by its spectral data. The relevant spectral data fromthe unknown spectra subdirectory 296 may then be transferred to theabnormal spectra subdirectory 292.

The plasma spectra directory 284 of FIG. 9 also contains data which isindicative of when the endpoint has been reached of an entire plasmaprocess or a discernible portion thereof such as a plasma step of asingle or multi-step plasma recipe or other plasma process. "Endpoint"in the context of a plasma process or a discernible portion thereof isthat time in the plasma process when the plasma within the processingchamber 36 has achieved a certain predetermined result. Each plasma stepin a plasma recipe typically has one or more characteristics in itscorresponding spectra which will indicate that the desired predeterminedresult has been achieved, as typically does the end of a plasma cleanwhich was initiated without first wet cleaning the chamber 36, a plasmaclean which was initiated after wet cleaning the chamber 36, and aconditioning wafer operation. Spectral data of a plasma processconducted in a chamber 36 may be analyzed after the plasma process isterminated to identify one or more spectra (or portions thereof such asone or more individual wavelengths) which are indicative that endpointof the subject plasma process or plasma process step has been reached.Spectral data which is indicative of endpoint from the variousabove-noted categories of plasma processes may be stored in asubdirectory of the plasma spectra directory 284 of FIG. 9 which isentitled "Spectra of Endpoint Characteristic(s)" and identified byreference numeral 316 (hereafter "endpoint subdirectory 316"). Thecurrent plasma process module 250 may use the information contained inthe endpoint subdirectory 316 to issue an appropriate alert(s) of theidentification of an endpoint condition, to address one or more aspectsof or relating to the control of the chamber 36, or both.

Multiple runnings of plasma processes within the chamber 36 may "age"the chamber 36 due to the nature of the plasma processes, and this agingmay adversely affect the performance of the chamber 36 in some manner.Indications that the chamber 36 may be in need of some type of cleaningmay be reflected by the spectra of the plasma in the chamber 36.Spectral data may be included in the plasma spectra directory 284 ofFIG. 9 which corresponds with a condition where "cleaning" of theinterior of the processing chamber 36 would be desirable. "Dirty chambercondition" spectral data may be recorded in the abnormal spectrasubdirectory 292, in which case the "dirty chamber condition" would thenbe characterized as a known error or aberration consistent with thediscussion above on the abnormal subdirectory 292. Alternatively, aseparate subdirectory may be employed as illustrated in FIG. 9 in thenature of a "Spectra of "Dirty Chamber Conditions" Subdirectory" andidentified by reference numeral 300 (hereafter "chamber conditionsubdirectory 300"). The current plasma process module 250 may use thisinformation on "dirty chamber conditions" to identify when a processingchamber 36 is in condition for cleaning, and further such thatappropriate actions may thereafter be undertaken.

A final subdirectory of the plasma spectra directory 284 of FIG. 9 is acalibration light spectra subdirectory 310 which does not containspectra of plasma from the chamber 36. Instead, one or more spectra ofone or more calibration lights are stored in the subdirectory 310.Generally, a calibration light, whose spectra is in the calibrationlight subdirectory 310, is directed at the window 38 of the processingchamber 36. A comparision is made between the spectral pattern of thecalibration light from the subdirectory 310 and the spectral pattern ofthat portion of the calibration light which is reflected by the innersurface 40 of the window 38 on the processing chamber 36. The results ofthe comparison are used to determine the type and amount of calibrationwhich should be implemented in relation to the operation of the currentplasma process module 250 as will be discussed in more detail below inrelation to the calibration module 562 and FIGS. 40-48.

The above-described structure of the plasma spectra directory 284 andits various subdirectories presented in FIG. 9 is just that--a generalstructure which organizes categorically similar data for use by thecurrent plasma process module 250 and its various sub-modules. Themanner in which the data used by the current plasma process module 250is actually stored is not particularly relevant for purposes of thepresent invention. However, it should be appreciated that data should bestored in a manner which allows the current plasma process module 250 toexecute its monitoring/evaluation function in a timely fashion.Preferably, this is on at least a substantially "real-time" basis andsub-second acquisition, analysis, and control is available through themodule 250. More specifically, acquisition of data, analysis of thissame data, and initiation of a protocol(s) based upon this analysis mayall be completed in less than a second through the current plasmaprocess module 250.

Continuing to discuss the storage of spectral data used by the currentplasma process module 250 in relation to the directory/subdirectorystructure discussed above in relation to FIG. 9, one embodiment of howdata may be stored in this directory/subdirectory structure isillustrated in FIG. 10. The plasma spectra directory 284 may have thesame subdirectories as presented in FIG. 9, although only the normalspectra subdirectory 288 and abnormal spectra subdirectory 292 areillustrated for convenience and only data on one category of plasmaprocess which may be stored in the normal subdirectory 288 isillustrated (plasma recipes). Review of the normal spectra subdirectory288 of FIG. 10 indicates that spectra on multiple plasma recipes, whichhave been previously run on product in the processing chamber 36 whichis associated with the plasma spectra directory 284, are each stored intheir own main data entry 350. This would also be the case with othercategories of plasma processes stored in the normal subdirectory 288.That is, each main data entry 350 is reserved for storing informationwhich is used to evaluate plasma processes which are to be conducted inthis same processing chamber 36.

Each main data entry 350 for a given plasma process has a plurality ofdata segments 354 associated therewith, and each of these data segments354 will include at least a spectra (e.g., FIG. 8) of the plasma in theprocessing chamber 36 at a certain point in time and preferably withinthe Preferred Optical Bandwidth at the Preferred Data Resolution. Thespectra associated with each data segment 354 may be stored as a singlespectra which covers the Preferred Optical Bandwidth, or may be storedas multiple spectra which collectively cover the Preferred OpticalBandwidth. Spectra for the data segments 354 are taken periodicallythroughout the running of a plasma process within the processing chamber36 through the window 38 on the chamber 36 (e.g., by the plasmamonitoring assembly 174 of FIG. 6 or any of the embodiments illustratedin FIGS. 31 and 37 below) using the Preferred Data Collection TimeResolution. Although the entirety of the plasma process may be recordedin the normal spectra subdirectory 288 in this manner, sometimes theplasma is rather unstable when it first comes on in the chamber 36.Therefore, it may be desirable to not retain optical emissions data inthe normal spectra subdirectory 288 from this unstable time period.

Entries of plasma processes in the normal spectra subdirectory 288 mayconsist of a plurality of totally different types or species of plasmaprocesses within a given category or genus as also illustrated in FIG.10. Plasma recipe A is stored under main data entry 350a, which isdifferent from a plasma recipe B which is stored under main data entry350b, which is different from a plasma recipe "X" which is stored undermain data entry 350c. Multiple runnings of the same plasma recipe orprocess may also be recorded in the normal spectra subdirectory 288 aswell if desired (not shown). For instance, spectral data from twoseparate runnings of plasma recipe A on the same type of product in theassociated processing chamber 36 may actually be included in the normalspectra subdirectory 288. Evaluation of a current plasma recipe beingrun on product in the subject processing chamber 36 would thenpotentially involve the comparison of optical emissions data on thecurrent process in relation to both of these main data entries 350.

The optical emissions data within the normal spectra subdirectory 288 ofFIG. 10 may be consolidated or condensed to eliminate the storage ofredundant data, to increase the speed of the search of the normalspectra subdirectory 288 by the current plasma process module 250, orboth. FIG. 11 illustrates one way in which this may be accomplished inthe case of the normal spectra subdirectory 288a for one example wherePlasma Recipes A-D are stored in the directory 288a. The same principleswould apply to any type of plasma process which is stored in the normalspectra subdirectory 288.

Plasma Recipe A under main data entry 358a and Plasma Recipe B undermain data entry 358b each have the same spectra for purposes of thecurrent plasma process module 250 from time t₁ (the first time data isrecorded in the subdirectory 288a for the subject plasma recipe) to timet_(n) (the "nth" time data is recorded in the subdirectory 288a for thesubject plasma recipe). Instead of storing the spectra over this timerange twice in the normal spectra subdirectory 288a (once under maindata entry 358a for Plasma Recipe A and once under main data entry 358bfor Plasma Recipe B), the multiple spectra from this time range arestored only once in common data segments 362a-c. More than 3 common datasegments 362 may obviously be used. Nonetheless, common data segments362a-c are thereby associated with both Plasma Recipe A of main dataentry 358a and Plasma Recipe B of main data entry 358b. At time t_(n+1)(i.e., the first time data is recorded in the normal spectra directory288a after the time t_(n+x)) and until the end of the plasma recipe inthe example presented by FIG. 11, however, the spectra of Plasma RecipeA under main data entry 358a and the spectra Plasma Recipe B under maindata entry 358b differ for purposes of the current plasma process module250. As such, Plasma Recipe A under main data entry 358a and PlasmaRecipe B under main data entry 358b each then include their ownindividual data segments 366a-c and 366d-f, respectively, over the timeperiod from t_(n+1) to t_(n+x) (the "xth" time data is recorded in thenormal spectra subdirectory 288a after the time t_(n)). Each of thePlasma Recipes A and B end at the same time for purposes of the exampleof FIG. 11 (i.e., at time t_(n+x)), although in a commercial settingthis may not be the case.

The normal spectra subdirectory 288b of FIG. 11 also has main dataentries 358c and 358d for Plasma Recipes C and D, respectively. The samedata storage concept used in relation to Plasma Recipes A and B islikewise employed for Plasma Recipes C and D in the normal spectrasubdirectory 288a. The spectra of Plasma Recipe C under data main entry358c and Plasma Recipe D under main data entry 358d are the same forpurposes of the current plasma process module 250 from time t₁ to timet_(n). Instead of storing the spectra over this time range twice in thenormal spectra subdirectory 288b (once under main data entry 358c forPlasma Recipe C and once under main data entry 358d for Plasma RecipeB), the multiple spectra from this time range are stored only once incommon data segments 362d-h in the normal spectra subdirectory 288a.Common data segments 362d-h are thereby associated with both PlasmaRecipe C of main data entry 358c and Plasma Recipe D of main data entry358d. At time t_(n) and until the time t_(n+x) of the plasma recipe inthe example presented by FIG. 11, however, the spectra of Plasma RecipeC under main data entry 358c and the spectra of Plasma Recipe D undermain data entry 358d differ for purposes of the current plasma processmodule 250. As such, Plasma Recipe C under main data entry 358c has itsown individual data segments 366g-k over the time period from t_(n+1) tot_(n+x), while Plasma Recipe D under main data entry 358d in turn hasits own individual data segments 366l-p over this same time period. Attime t_(n+x) and until the end of the plasma recipe in the examplepresented by FIG. 11 at t_(n+y), however, the spectra of Plasma Recipe Cunder main data entry 358c and the spectra of Plasma Recipe D under maindata entry 358d again are the same for purposes of the current plasmaprocess module 250. As such, Plasma Recipe C under main data entry 358cand Plasma Recipe D under main data entry 358d have common data segments362i-z over the time period from t_(n+x) to t_(n+y). Each of the PlasmaRecipes C and D end at the same time for purposes of the example of FIG.11, although in a commercial setting this again may not be the case.

Each data segment 354 of each plasma process stored under a main dataentry 350 in the normal spectra subdirectory 288 of FIG. 10 may containa multiplicity of data types relevant to the monitoring of the currentplasma process with the current plasma process module 250. Arepresentative example is presented in FIG. 12A where these various datatypes of data are presented in data fields 322 which are associated witheach data segment 354. Spectral patterns of the plasma in the processingchamber 36 is a significant data type for comparing the current plasmaprocess with the plasma spectra directory 284, and these spectra arestored in a spectra field 322d in the normal spectra subdirectory 288 ofFIG. 12A. Each data segment 354 in the normal spectra subdirectory 288also includes a time field 322a where the time associated with thespectra in the spectra field 322d is recorded (e.g., the time into theplasma process when the spectra is taken). Data in the time field 322amay be used in various ways by the current plasma process module 250 aswill be discussed in more detail below.

Further information is at least associated with each main data entry 350in the normal spectra subdirectory 288. "Associated" in this contextmeans that this information may be provided once for each main dataentry 350 for a given plasma process or for only a few times which isless than the total number of data segments 354 under a particular maindata entry 350, but it also encompasses a situation where thisinformation is actually provided for each data segment 354 of thesubject main data entry 350 which is not as desirable because ofredundancies. Fields for these types of information include: a plasmaprocess "genus" field 322h (e.g., to identify whether the main dataentry 350 is a plasma recipe, plasma clean, or conditioning waferoperation); a wafer identifier field 322b (e.g., for information whichcorresponds with an identifier, such as a number or code, which appearson the wafer 18 which is to have a plasma recipe run thereon and whichis used for tracking purposes); a plasma process "species" field 322c (asubset of a plasma process "genus", such as different types of plasmarecipes (e.g., plasma recipe A and plasma recipe B)); a plasma processstep field 322e (e.g., to identify the step of a particular plasmarecipe or any other plasma process which provides a different functionor achieves a different result than other portions of the process); amaximum total plasma process step time field 322f (e.g., the maximumamount of time allowed to complete a given plasma step of a multi-stepplasma recipe or other process); and a maximum total plasma process timefield 322g (e.g., the maximum amount of time allowed to complete anentire plasma process (each of its steps)). Certain of this informationwill be inapplicable to certain genus of plasma processes and/or certainspecies of plasma processes within a certain plasma process genus.Information provided to the above-noted fields may be input with thedata entry device 132 of FIG. 6, although the information for the waferidentifier field 322b may be automatically read from the wafer 18 andinput to the subject main data entry 354 (e.g., scanner).

The plasma spectra directory 284 of FIG. 10 also illustrates one way ofstoring data for entries in the abnormal spectra subdirectory 292. Areview of the abnormal spectra subdirectory 292 of FIG. 10 indicatesthat spectral data on multiple known errors or aberrations are eachstored in a main data entry 346 for evaluating future plasma processeswhich are conducted in the same processing chamber 36 where these errorsor aberrations occurred. As noted above, these errors in the main dataentries 346 have preferably been identified (e.g., the cause(s) of theerror has been determined), and are thereby a "known" condition whichmay be encountered when running a plasma process in the processingchamber 36. Each main data entry 346 having one specific error thereinis illustrated as having a plurality of data segments 354 associatedtherewith, and each of these data segments 354 will include at least aspectra (e.g., FIG. 8) of the plasma from the processing chamber 36which is a deviation from the relevant spectra of the correspondingplasma process in the normal spectra subdirectory 288 and which isindicative of the subject error or aberration. The spectra associatedwith each data segment 354 under the abnormal spectra subdirectory 292may be of the Preferred Optical Bandwidth using the Preferred DataResolution. Alternatively, the spectra associated with the data segments354 under the abnormal spectra subdirectory 292 may only include thatportion of the spectrum which contains the characteristic(s) which areindicative of the error in question (i.e., an optical emissions segmentwhich is contained within, but smaller than, the Preferred OpticalBandwidth).

Further information relevant to the abnormal spectra subdirectory 292 isillustrated in FIG. 10. Spectral patterns for the data segments 354under each main data entry 346 of the abnormal spectra subdirectory 292are illustrated as having been recorded periodically during the runningof the entire plasma process within the processing chamber 36 (e.g.,using the Preferred Data Collection Time Resolution). Data on the entireplasma process could be retained in the abnormal subdirectory 292. Inthis case the time t₁ referenced in the data segments 354m, 354q, and354u would be the first spectra obtained of the subject plasma process,while the time t_(n) would be the last spectra obtained of the subjectplasma process at the termination thereof (e.g., endpoint of the laststep in the process, or the endpoint of the plasma process if there isnot more than one step). This situation may result in the storage ofunnecessary data in the abnormal spectra subdirectory 292. Consider asituation where a plasma recipe is being run on product within theprocessing chamber 36 and has proceeded according to the normal spectrasubdirectory 288 for the first 90 seconds of the plasma recipe. Assumethat only about 10 additional seconds are required to complete theplasma recipe (i.e., to achieve the result associated with the last stepof the recipe). Also assume that an error occurs at the 91 second markin the current plasma recipe. Unless the data on the first 90 seconds ofthe plasma recipe provides some type of indication as to the upcomingerror which again occurred at the 91 second mark in the current plasmarecipe of this example, this data will not be useful for retention inthe abnormal spectra subdirectory 292. In this case the spectra at thetime t₉₁ could be the first spectra which did not "match" with any ofthe plasma recipes in the normal spectra subdirectory 288. No otherspectra need be included under the main entry 346 if this one spectrasufficiently identifies the error (not shown). However, it may bedesirable to record in the abnormal spectra subdirectory 292 all spectrawhich are obtained after the error has been identified and up until theplasma process is terminated at the time t_(n), or at least a fewspectra at various time intervals. Flexibility is provided by theabnormal subdirectory 292 in that the amount of data included under eachof the main data entries 346 in which the errors are contained may beindependently selected. Therefore, the data segments 354 under each maindata entry 346 of the abnormal spectra subdirectory 292 may notnecessarily provide a complete history of a plasma process in which anerror occurred.

Multiple data types may be included in each data segment 354 associatedwith each error in each main data entry 346 of the abnormal spectrasubdirectory 292 of FIG. 10. A representative example is presented inFIG. 12B where these various data types are contained within data fields338 which are associated with each data segment 354 under each main dataentry 346 of the subdirectory 292. Spectral patterns of the plasma inthe processing chamber 36 are a significant data type for comparing thecurrent plasma process with the plasma spectra directory 284, and thesespectra are stored in a spectra field 338b of the abnormal spectrasubdirectory 292 of FIG. 12B of each data segment 354. Moreover, thecategory or genus of the subject plasma process may be identified in aplasma process genus field 338e (e.g., plasma recipe, plasma clean,conditioning wafer operation), a particular type or species of a givencategory or genus of plasma process may be identified in a plasmaprocess species field 338f (e.g., a particular type of plasma recipe),and the type of plasma step may be identified in a plasma process stepfield 338g.

Data in addition to the above-described spectra may be associated witheach of the data segments 354 under each main data entry 346 for knownerror/aberrations within the abnormal spectra subdirectory 292. Eachdata segment 354 of each main data entry 346 may also include a timefield 338a for containing information on the time which is associatedwith the spectra in the subject data segment 354. Other informationassociated with the data segments 354 under each main data entry 346 forknown error/aberrations within the abnormal spectra subdirectory 292includes information which identifies the error. Any textualidentification or description of the error stored under a main dataentry 346 may be included in an error field 338c of the abnormal spectrasubdirectory 292. This information would typically be manually enteredby personnel using the data entry device 132 (e.g., FIG. 6) after thespectra was analyzed and the cause(s) of the error(s)/aberration(s) wasidentified.

The current plasma process module 250 includes error identificationcapabilities as will be discussed in more detail below. Once the currentplasma process module 250 identifies a match between the current opticalemissions data and a relevant spectra or portion thereof in the abnormalspectra subdirectory 292, information on the correspondingerror/aberration may be issued based upon information in the error field338c. Moreover, corrective actions may be undertaken based upon thecontents of this same error field 338c. In this regard, each datasegment 354 under each main data entry 346 for known error/aberrationswithin the abnormal spectra subdirectory 292 may also include a protocolfield 338d. Information contained within the protocol field 338d willsomehow relate to how the subject error or aberration may or should beaddressed, or more specifically what action or actions may or should beundertaken to address the error. Single or multiple protocols may bestored in any one protocol field 338d (e.g., more than one protocol maybe appropriate to address a certain condition). Once the current plasmaprocess module 250 identifies a match between the current spectra and arelevant spectra in the abnormal spectra subdirectory 292, how thecorresponding error/aberration is addressed may be based uponinformation contained in the subject protocol field 338d.

Data regarding process control parameters or conditions associated withthe processing chamber 36 may also be included in each of theabove-described subdirectories of the plasma spectra directory 284 for aspecific data entry, particularly in the case of the abnormal spectrasubdirectory 292 and the unknown conditions subdirectory 296. Thesewould include conditions which are typically monitored in a plasmaprocess, such as the types of feed gases being used or the compositionof the plasma, temperatures within one or more regions of the chamber36, the pressure within the processing chamber 36, power settings, andgas flow rates.

Pattern Recognition Module 370--FIG. 13

Certain key principles of the present invention are simply based onwhether one spectral pattern matches another spectral pattern (e.g.,does the spectral pattern of the plasma in the chamber 36 "match" thepattern of the relevant spectra in the relevant subdirectory of theplasma spectra directory 288). In many cases this determination may bemade through the pattern recognition module 370 which is presented inFIG. 13. Various "pattern recognition techniques" may be employed by thepattern recognition module 370 to provide the above-noted function. Onesuch pattern recognition technique is embodied by the flowchart depictedin FIG. 13 and may be generally characterized as a point-by-pointpattern recognition technique. The point-by-point pattern recognitiontechnique which is embodied by the pattern recognition subroutine 374 ofFIG. 13 is contained within step 378. The intensity at a firstwavelength in the current spectra at the current time t_(c) (a fixedpoint in time) is compared with the intensity at this same firstwavelength of the relevant spectra from a Target Directory. Whicheversub-module of the current plasma process module 250 calls the patternrecognition module 370 will designate which particular subdirectory ofthe plasma spectra directory 284 is to be searched by the module 370 for"matching" patterns (and thereby defines the Target Directory). Thesub-module which calls the pattern recognition module 370 may alsoestablish what will constitute a "matching" pattern. That is, what maybe a "matching spectra" in relation to one sub-module of the currentplasma process module 250 may not be a "matching spectra" in relation toanother of its sub-modules.

If the intensities of the two subject spectra are within a "match limit"of each other at this first wavelength in the subject optical emissions,the patterns of the two subject spectras are initially considered a"match" and the analysis is repeated at a second wavelength which isdisplaced and different from the first wavelength and which defines asecond "point" on which the above-noted point-by-point analysis isrepeated. The particular "match limit" which is used by the patternrecognition subroutine 374 may be specific to which sub-module of thecurrent plasma process module 250 calls the pattern recognitionsubroutine 374 as noted. The above-described point-by-point analysis isrepeated by "advancing along" the entirety of the current spectra attypically pre-selected wavelength increments (e.g., every nanometer).Typically, a fixed wavelength increment will be utilized by step 378,such that the comparison between the two subject spectra will be made atevery "x" nanometers throughout the entirety of the entire "bandwidth"of the spectra. However, there need not be equal spacings between eachof the "points" examined by the pattern recognition subroutine 374.

Another match criterion which may be used in combination with theabove-noted point-by-point comparison relates to how many of theexamined points must be within the "match limit" in order for the twosubject spectra to be considered a match. The sub-module which calls thepattern recognition subroutine 374 may require each "point" examined inthe subject point-by-point analysis to be within the selected matchlimit in order for the two spectra to be considered a match.Alternatively, something less than 100% may also be utilized. Forinstance, having at least 95% of the points being within the match limitmay equate with the two subject spectras being considered a match.Furthermore, the average variation of the multiplicity of pointsexamined by the pattern recognition subroutine 374 may be calculated andcompared with an average associated with the relevant spectra from theTarget Directory to determine if it is within a predefined tolerance.Any combination of the foregoing may be implemented for determining whatis a "match."

A number of factors will affect the accuracy which may be attributed tothe results achieved by the execution of step 378 in the patternrecognition subroutine 374 of FIG. 13. One such factor is the "matchlimit" which will be discussed in relation to the point-by-pointcomparison technique, but which will be equally applicable to theaveraging discussed above. In this case, the "match limit" is the amountthat the intensity associated with a point in the current spectra at acertain point in time t_(c) will be allowed to deviate from theintensity of the relevant spectra from the Target Directory, and yetstill be considered a "match" for purposes of the pattern recognitionsubroutine 374. Two types of "match limits" which may be utilizedinclude a raw difference basis and a percentage difference basis. In thecase of a "raw difference basis", a fixed number of intensity units isestablished and input to the pattern recognition subroutine 374 andwhich thereby defines the boundary of a "match" (e.g., the "rawdifference basis" limit may be established at ±"x" intensity units where"x" is a value which is input to the pattern recognition subroutine 374,such that the intensity at each wavelength of the current spectrachecked by the pattern recognition subroutine 374 must be within ±"x"intensity units of the intensity at each of the correspondingwavelengths of the relevant spectra from the Target Directory in orderto be considered a "match"). In the case of having a "match limit" basedupon a "percentage difference basis," a fixed percentage is establishedand input to the pattern recognition subroutine 374 and which therebydefines the boundary of a "match" between corresponding intensities ofthe current spectra and the relevant spectra from the Target Directory(e.g., the "raw difference basis" limit may be established at ±"x"percent, such that the intensity at each wavelength of the currentspectra checked by the pattern recognition subroutine 374 must be within±"x" percent of the intensity at each of the corresponding wavelengthsof the relevant spectra from the Target Directory in order to beconsidered a "match"). Both the "raw difference" and "percentagedifference" may be used simultaneously as a "match limit" by the patternrecognition subroutine 374 as well (i.e., both criterion must besatisfied in order for the spectras to be considered a "match"). The"match limits" are equally applicable to when the above-noted averagingtechnique is used as well. Regardless of which type of "match limit" isemployed, it is entered for use by the pattern recognition subroutine374.

Another factor which affects the accuracy which may be attributable tothe results of the pattern recognition subroutine 374 of FIG. 13 is theanalytical wavelength resolution used in the above-describedpoint-by-point analysis. "Analytical Wavelength Resolution" in thiscontext means the wavelength increments at which the above-describedpoint-by-point analysis will be performed throughout the subjectspectra. Although the plurality of wavelengths for the above-notedpoint-by-point analysis could be random throughout the bandwidth of thesubject spectra, preferably a pattern is used such as a fixed wavelengthincrement. For instance, if the analytical wavelength resolution isestablished at 1 nanometer and input to the pattern recognitionsubroutine 374, the above-noted point-by-point analysis of step 378would be performed at each 1 nanometer increment across the entirety ofthe Preferred Optical Bandwidth. Preferably the Analytical WavelengthResolution used by the pattern recognition subroutine 374 is no morethan about 2 nanometers, and even more preferably no more than about 0.5nanometers. Hereafter, this will be referred to as the "PreferredAnalytical Wavelength Resolution."

Summarizing step 378 of the pattern recognition subroutine 374 of FIG.13 in the case where the current spectra extends from 200 nanometers to900 nanometers and where the Analytical Wavelength Resolution is 1nanometer, a comparison is made of the intensities at the 200 nanometerwavelength from the current spectra at the current time t_(c) (from thecurrent plasma process being run within the processing chamber 36) andfrom the relevant spectra from the Target Directory. If the differencebetween these two intensities is within the "match limit" input to thepattern recognition subroutine 374, whether using a raw differencetheory, a percentage difference theory, or a combination of a rawdifference theory and a percentage difference theory (e.g., thedifference in intensity must be no more than a certain, input number ofintensity units and must also be within a certain, input number ofpercentage points of each other in the case of a combination), the 200nanometer wavelength "point" of the current spectra and the relevantspectra from the Target Directory will be characterized as a "match" atthe current time t_(c). The point-by-point analysis will then continueat the 201 nanometer wavelength in the above-described manner, and willbe repeated at each 1 nanometer increment until reaching the last 900nanometer wavelength. Results of the point-by-point comparison of step378 for the current spectra at the current time t_(c) will then beprovided to step 380 of the pattern recognition subroutine 374 of FIG.13 for use by the sub-module of the current plasma process module 250which called the pattern recognition module 370. Control of the plasmamonitoring operations is then returned by step 382 of the patternrecognition subroutine 374 to the sub-module of the current plasmaprocess module 250 which called the pattern recognition module 370.

Some plasma processes change very rapidly and some plasma processes areof relatively short duration (e.g., some plasma steps of a plasma recipeare no more than about 5 seconds). Therefore, spectral data should betaken at least every 1 second and the analysis of this data should becompleted by the pattern recognition subroutine 374 as fast as possible.In the case where the plasma process is a plasma recipe which will bediscussed in more detail below in relation to the plasma healthsubroutine 253 of FIG. 21, the identification of the current plasmarecipe and the analysis of the performance of the processing chamber 36(e.g., plasma health) should be completed at least before the next wafer18 is loaded into the chamber 36 for another running of a plasma recipeon this product within the chamber 36. The pattern recognitionsubroutine 374 of FIG. 13 is able to meet the demands throughsimplifying the analysis of the spectra of the plasma in the processingchamber 36. The sum total of the analysis provided by the patternrecognition subroutine 374 is simply whether the pattern of the currentspectra "matches" the pattern of the relevant spectra from the TargetDirectory. There is no need to locate or define peaks in the spectra ofthe plasma from the process currently being conducted in the processingchamber 36 in the analysis used by the pattern recognition subroutine374 at each of the limits. Nor is any attempt made by the patternrecognition subroutine 374 to identify the various chemical speciescurrently in the plasma in the processing chamber 36 through spectralanalysis. Again, the only determination made by the subroutine 374 iswhether the current spectral pattern "matches" the relevant spectralpattern in the Target Directory. In one embodiment the patternrecognition subroutine 374 is able to execute step 378 for a spectradefined by wavelengths at least within the range of about 150 nanometersto about 1,200 nanometers with an analytical wavelength resolution of nomore than about 1 nanometer (i.e., execute the point-by-point analysisat least at every 1 nanometer increment) in no more than about 1 second,and preferably in no more than about 0.5 seconds.

Process Alert Module 428--FIG. 14

Various conditions which may be encountered by the current plasmaprocess module 250 may result in the transfer of control to or thesharing of control with the process alert module 428 of FIG. 14. One ormore subroutines may be included under the process alert module 428.Each of these subroutines may present various options in relation to howthe relevant condition or situation is addressed which resulted in theactivation of the process alert module 428. In the case of the processalert subroutine 432 of FIG. 14, two categories of "actions" are madeavailable--the issuing of one or more alerts and addressing the controlof the subject plasma process in some manner.

One or more alarms, alerts, or the like may be activated if the alarmalert function of the process alert subroutine 432 of FIG. 14 is enabledat its step 454 in relation to the subject condition or situation. Atleast one visual alarm may be activated in step 458 of the process alertsubroutine 432. Exemplary visual alarms include displaying a generalindication of the existence of the relevant condition (e.g., a flashinglight), a more specific indication of the subject condition (e.g.,providing a textual description of the identified condition orsituation), or both. Appropriate locations where information relating tothe subject condition may be presented include the display 130associated with the particular processing chamber 36 where the subjectcondition was encountered, the display 59 associated with the waferproduction system 2 which may be characterized as a master control panelof sorts for the wafer production system 2, any master control panel forthe entire fabrication facility incorporating the wafer productionsystem 2, any computer network on which the wafer production system 2 isincluded, or on any combination of the foregoing. Other visualindications may be employed alone or in combination with any of theforegoing. Audio and any other types of alarms may also be employed.

Another option available under the process alert subroutine 432 of FIG.14 relates at least in some manner to the control of the plasma processand which may be accessed through step 436 of the process alertsubroutine 432. Any spectra which is associated with a condition, or theidentification of the condition itself, which will trigger theactivation of the process alert subroutine 432 may be included in orassociated with a step 448 of the subroutine 432. One or more protocolswhich have been established for when this spectra or condition isencountered in the chamber 36 may be included in an associated step 450.Multiple spectra or conditions may be included in any one step 448. Thecommonality between these spectra/conditions included in or associatedwith a step 448 is the categorically similar protocol included in itsassociated step 450.

Five categorical protocols are presented in FIG. 14. Step 450a presentsa protocol category which is the modification of one or more processcontrol parameters. One or more spectra from the abnormal spectrasubdirectory 292, one or more conditions, or both, may be included instep 448a of the process alert subroutine 432 which will access step450a. Step 450a is directed toward a protocol category which is toattempt to "address" (e.g., correct/remedy) the subject condition in thecurrent plasma process being run in the chamber 36. The protocolassociated with step 450a of the process alert subroutine 432 morespecifically provides for the modification or adjustment of one or moreprocess control parameters in a manner which has been previouslydetermined to be appropriate to address the subject condition.Adjustment of the process control parameters associated with the currentplasma process may be automatically undertaken if desired by thefacility incorporating the wafer production system 2 through operativelyinterfacing the process alert subroutine 432 with the appropriateprocess controller(s) (e.g., by sending an appropriate signal from thePMCU 128 to the MCU 58 of FIG. 1 which controls the wafer productionsystem 2). Manual adjustment of one or more process control parametersis also contemplated by step 450a of the process alert subroutine 432.Execution of step 450a in this case would entail informing theappropriate personnel of the protocol(s) associated with the subjectcondition such that these personnel could manually initiate theappropriate action if desired.

Notwithstanding the presentation of a single "modify process controlparameters" protocol in FIG. 14, it should be appreciated that differentprocess control modifications may be initiated for differentspectra/conditions associated with step 448a. One or more spectra may beassociated with a condition which requires modification of the processcontrol parameters in one way, while one or more spectra associated withanother condition may require modification of the process controlparameters in another way. Moreover, any one or more spectra or one ormore conditions associated with step 448a may have one or more processcontrol protocols associated therewith. For instance, in the case wherestep 450a is not directly integrated with the relevant processcontroller(s), a listing of possible corrective actions which may beundertaken to address the associated condition(s) may be provided forconsideration by the appropriate personnel. Integrating step 450a withone or more controllers associated with the wafer production system 2may still utilize multiple process control protocols for any one or morespectra/conditions. Attempts to address the subject condition associatedwith step 448a may first be pursued through a first protocol associatedwith this condition and step 450a. If this is unsuccessful in addressingthe subject condition, a second protocol associated with the subjectcondition and step 450a may then be undertaken and so forth.

Another categorical protocol which may be included in the process alertsubroutine 432 of FIG. 14 relates to terminating the current plasmaprocess. One or more spectra which are representative of one or moreconditions, or the identification of the condition(s) itself, may beincluded in or associated with step 448b of the subroutine 432 whichaccesses step 450b. Step 450b contains one or more protocols which aredirected toward terminating the subject plasma process, althoughtypically termination of the current plasma process will simply entailterminating the gas flow to the chamber 36 and the electricalcomponentry which are responsible for creating the plasma. Terminationof the current plasma process may be automatically undertaken if desiredby the facility incorporating the wafer production system 2 throughoperatively interfacing the process alert subroutine 432 with theappropriate process controller(s) (e.g., by the PMCU 128 sending anappropriate signal to the MCU 58). Manual termination of the currentplasma process is also contemplated by step 450b. Execution of step 450bin this case may then simply entail apprising the appropriate personnelthat a condition has been identified where termination of the currentplasma process being run in the processing chamber 36 is recommendedsuch that the appropriate action may be manually undertaken if desired.

Cleaning operations may also be initiated through the process alertsubroutine 432 of FIG. 14. One or more spectra from the abnormal spectrasubdirectory 292 or the chamber condition subdirectory 300, or againsimply the identification of the relevant condition, may be includedin/associated with step 448e of the subroutine 432 which in turnaccesses step 450e. Step 450e contains a protocol which is directedtoward initiating some type of a cleaning of the interior of theprocessing chamber 36. Cleaning operations may be automaticallyundertaken if desired by the facility incorporating the wafer productionsystem 2 through operatively interfacing the process alert subroutine432 with the appropriate process controller(s) (e.g., by the PMCU 128sending an appropriate signal to the MCU 58). Manual implementation ofthese actions is also contemplated by step 450e. In this regard, theexecution of step 450e in the process alert subroutine 432 of FIG. 14may simply entail apprising personnel that it is recommended that thecurrent plasma process being run in the processing chamber 36 beterminated due to the detected dirty chamber condition, and that acleaning operation be subsequently manually initiated.

One or more spectra/conditions associated with step 448e may beassociated with different protocols in step 450e. For instance, oneprotocol of step 450e corresponding with one or more spectra/conditionsassociated with step 448e may relate to a plasma cleaning operationwhich may be initiated in accordance with the foregoing. Other spectraor conditions associated with step 448e may access a protocol of step450e which relates to a wet clean which may be initiated in accordancewith the foregoing.

Spectra or conditions within the chamber 36 which are of a nature suchthat the wafer distribution sequence should be affected in some mannerby their existence may be included in or associated with step 448c. Theprotocol set forth in step 450c thereby addresses the manner in whichwafers 18 are distributed to the various processing chambers 36 of thewafer production system 2 through the wafer distribution module 1384which will be discussed in more detail below in relation to FIGS. 59-60.Addressing the sequence of distribution of wafers 18 to the processingchambers 36 of the wafer production system 2 may be automaticallyundertaken if desired by the facility incorporating the wafer productionsystem 2 through operatively interfacing the process alert subroutine432 with the appropriate process controller(s) (e.g., wafer distributionmodule 1384, MCU 58). Manual techniques are also contemplated by step450c in that the execution of step 450c of the process alert subroutine432 may simply entail apprising personnel that it is recommended thatthe distribution sequence to the chambers 36 of the system 2 be manuallyaddressed because of the existence of the subject condition.

Finally, plasma process/plasma process step endpoint may be addressedthrough the process alert subroutine 432 of FIG. 14. In this regard, oneor more spectra indicative of the endpoint of the subject plasma processor discrete portion thereof (e.g., plasma process step), or theidentification of the plasma process/process step itself, may beincluded in or associated with step 448d. The protocol set forth in step450d addresses how the identification of the occurrence of theparticular endpoint should be addressed. This may include terminatingthe subject plasma process/process step, initiating the next plasmaprocess/step (e.g., if the subject plasma step is not the last step of agiven plasma recipe or other process), or both depending upon the natureof the plasma process. Automation and manual techniques are contemplatedby step 450d as in the above-noted cases.

The control of the plasma monitoring operations is relinquished by theprocess alert subroutine 432 of FIG. 14 through steps 440 (if only thealarm alert function is enabled at step 454) or 462 (if the processcontrol feature is enabled at step 436). Depending upon thecircumstances, control may be returned to the particular sub-module ofthe current plasma process module 250 which called the process alertmodule 370. Another option which may be employed is to return control ofthe plasma monitoring operations in a particular case or in all cases tothe startup module 202 of FIG. 7 through execution of steps 440 or 462.

Startup Module 202--FIGS. 15-16

Information on what is happening in the processing chamber 36 (e.g.,spectra of the plasma in the chamber 36) is made available to thecurrent plasma process module 250 for evaluation of the current plasmaprocess operation through its various "sub-modules" as generallydiscussed above and as will be addressed in more detail below inrelation to the following relevant figures. Access to the various"sub-modules" of the current plasma process module 250 may be controlledthrough the startup module 202 of FIG. 15. As such, the startup module202 may be viewed as a main menu of sorts for the various options thatare available through the current plasma process module 250.

One embodiment of a startup routine which may be used by the startupmodule 202 is illustrated in FIG. 15 and provides the above-noted "mainmenu-like" function. The startup routine 203 basically allows personnelto "enter" in some manner the type of action to be undertaken such thatcontrol of the plasma monitoring operations may be transferred to theappropriate sub-module of the current plasma process module 250. "Entry"may be accomplished by providing a listing on the display 130 associatedwith the PMCU 128 (e.g., FIG. 6) of all of the actions which may beundertaken and allowing personnel to select which option should bepursued with the data entry device 132. Another option would be to allowpersonnel to input the action to be initiated using the data entrydevice 132. Still another option would be for the startup routine 203 tosequentially scroll down through a listing of the various options.Finally, no input need be provided as the current plasma process module250 may just immediately begin comparing the current plasma process tothe plasma spectra directory 284 (e.g., using an appropriate order forsearching the various subdirectories).

Three "categorical" actions may be initiated through the startup routine203. First, certain calibration operations may be undertaken throughstep 136 of the startup routine 203 which accesses a calibration module562 through execution of step 140. The calibration module 562 will bediscussed in more detail below in relation to FIGS. 40-48. Research inrelation to the current plasma process to be run in the chamber 36 maybe initiated through step 144. For instance, research may be undertakento identify one or more characteristics which are indicative of theendpoint of a particular plasma process or plasma process step. This isaccomplished through execution step 148 of the startup routine 203 whichcalls a research module 1300 which will be discussed in more detailbelow in relation to FIGS. 49-51C.

A final option available through the startup routine 203 of FIG. 15relates to current plasma processes (i.e., any plasma process run in thechamber 36 which is not recorded in the plasma spectra directory 284).Plasma processes such as plasma processing qualification/productionwafers (step 230), plasma cleaning operations without first doing a wetclean of the chamber 36 (step 234), plasma cleaning operations conductedafter the chamber 36 has been wet cleaned (step 238), and conditioningwafer operations (step 242) each may be accessed through the startuproutine 203. The endpoint of these types of plasma processes, a specificportion thereof, or both may be determined through an endpoint detectionmodule 1200 which will be discussed in more detail below in relation toFIGS. 52-58 and which is called by step 240 of the startup routine 203.The "health" of these types of plasma processes may also be evaluatedthrough the plasma health module 252 which will be discussed in moredetail below in relation to FIGS. 21-25 and which is called throughexecution of step 236 of the startup routine 203.

Step 236 of the startup routine 203 of FIG. 15 relates to a plasmahealth evaluation and calls the startup subroutine 204 of FIG. 16. Twomain options may be pursued in relation to "plasma health" through thestartup subroutine 204 of FIG. 16. Either a current plasma process maybe recorded in the normal spectra subdirectory 288 to be used as astandard for evaluating plasma processes subsequently run in the chamber36, or the current plasma process may be evaluated against the normalspectra subdirectory 288. In this regard, step 208 of the startupsubroutine 204 of FIG. 16 inquires as to whether the plasma process tobe conducted in the subject processing chamber 36 should be recorded inthe normal spectra subdirectory 288 associated with this chamber 36. Ifthe "response" to the inquiry of step 208 is a "yes", the startupsubroutine 204 proceeds to step 224 where a determination is made as tothe status of the plasma in the processing chamber 36 specificallywhether the plasma is "on" through optical analysis by the currentplasma process module 250. One way to determine if the plasma is "on" inthe chamber 36 is to determine when the spectra obtained from theprocessing chamber 36 "matches" any spectra stored in the plasma spectradirectory 284 or any of its subdirectories, such as through the patternrecognition module 370 of FIG. 13. Another way in which this may be doneis to determine when any of the spectra from the interior of theprocessing chamber 36 have at least a certain number of discrete peaksof a least a certain intensity. Using the same principles discussedabove in relation to the pattern recognition module 370 of FIG. 15 mayalso identify this type of spectra through the current plasma processmodule 250. Determining when there is at least a certain change in theoptical emissions from within the chamber 36 may also be indicative thatthe plasma is "on" (e.g., going from a "dark" condition to a "light"condition). Regardless of how the determination is made as to whetherplasma exists in the processing chamber 36, the "plasma on" indicationmay be appropriately conveyed to operations personnel or others in oneor more of the above-noted manners.

Once plasma is present in the processing chamber 36, the startupsubroutine 204 proceeds to step 228 where at least spectral data of thecurrent plasma process is recorded in the normal spectra subdirectory288. Preferably this encompasses the Preferred Optical Bandwidth at thePreferred Data Resolution and using the Preferred Data Collection TimeResolution. After the plasma process is terminated, the subroutine 204returns to the "main menu-like" startup routine 203 of FIG. 15 via step226.

The other alternative available through the startup subroutine 204 ofFIG. 16 is to evaluate the current plasma process to be run in thesubject processing chamber 36 against spectral data already recorded inthe normal spectra subdirectory 288. In the example presented in FIG.16, this is accomplished by exiting step 208 of the startup subroutine204 under a "no" logic condition, which directs the startup subroutine204 to proceed to step 212. Step 212 inquires as to whether the plasmaprocess to be run in the processing chamber 36 should be evaluatedagainst spectral data in the normal spectra subdirectory 288. Since thetwo main options available under the startup subroutine 204 are toeither record data or evaluate spectral data of the current plasmaprocess against spectral data already recorded in the normal spectrasubdirectory 288, and further since the subroutine 204 reached step 212because a "decision" was made at step 208 of the subroutine 204 to notrecord data in the normal spectra subdirectory 288, a response of "no"at step 212 merely redirects the startup subroutine 204 to start over.Responding "yes" at step 212, however, directs the startup subroutine204 to proceed from step 212 to step 216. Step 216 inquires as towhether the plasma is on in the processing chamber 36, and therefore maybe identical to step 224 discussed above. Once plasma exists within theprocessing chamber 36, the startup subroutine 204 proceeds to 220 wherecontrol of plasma monitoring operations is transferred to the plasmahealth module 252 such that the health of the plasma process may beassessed. The "record" or"compare" options may be presented in otherways than as set forth in the start-up subroutine 203.

Plasma Health Evaluations

The plasma health module 252 of FIGS. 7 is also included in theembodiment of FIG. 32 and evaluates the overall health of the plasma inthe subject chamber 36 or the "plasma health." "Plasma health" as usedherein means the state or the condition of the plasma process as itrelates to plasma performance when compared to typical "normal" plasmabehavior resulting in usable product. The "condition" of the plasma inturn may be characterized as the cumulative result of all parametershaving an effect on the plasma in the processing chamber. Stated anotherway, "plasma health" may be equated with a condition where a currentplasma process is proceeding in accordance with one or more plasmaprocesses stored in the normal spectra subdirectory 288. In this regard,the plasma health module 252 is able to determine if the current plasmaprocess being conducted within the processing chamber 36 is progressing"normally" through a comparison of at least a portion of the opticalemissions from the processing chamber 36 during the plasma process withthe relevant spectra or portion thereof in the normal spectrasubdirectory 288. Spectral patterns of the plasma in the chamber 36 willchange as the plasma process progresses. Moreover, the spectral patternsof the plasma in the chamber 36 differ in relation to the category ofplasma process being run. This is evidenced by a review of exemplaryspectra from a plasma recipe, a plasma clean conducted without first wetcleaning the chamber 36, a plasma clean executed after a wet clean ofthe chamber 36, and a conditioning wafer operation presented below. Ineach case, "intensity" is plotted along the "y" axis and expressed in"counts" which is reflective of the intensity level, while "wavelength"is plotted along the "x" axis in nanometers.

Exemplary Plasma Recipe Spectra--FIGS. 17A-C

An example of a multiple step plasma recipe run on a wafer 18 in thechamber 36 is illustrated in FIGS. 17A-C in which the spectra of theplasma in the processing chamber 36 varies with a change in the currentplasma step. FIGS. 17A-C present a spectra 744 of an exemplary firstplasma step of an exemplary plasma recipe A, a spectra 752 of anexemplary second plasma step of this same plasma recipe A, and a spectra760 of an exemplary third plasma step of this same plasma recipe A,respectively. Each of these spectra 744, 752, and 760 are characterizedby a number of peaks 748, 756, and 764, respectively, of varyingintensities at various wavelengths. A comparison of the spectra 744,752, and 760 reveals that their associated patterns differ, includingwithout limitation as follows: 1) at about the 425 nanometer wavelengthregion, peak 748a in the spectra 744 of FIG. 17A has an intensity ofabout 3,300, peak 756a in the spectra 752 of FIG. 17B has an intensityof about 3,000, and peak 764a in the spectra 760 of FIG. 17C has anintensity of about 2,100; 2) at about the 475 nanometer wavelengthregion, peak 748b in the spectra 744 of FIG. 17A has an intensity ofabout 3,200, peak 756a in the spectra 752 of FIG. 17B has an intensityof about 3,900, and there is no peak in the spectra 760 of FIG. 17C, butthe corresponding intensity (noise) is about 500; 3) at about the 525nanometer wavelength region, peak 748c in the spectra 744 of FIG. 17Ahas an intensity in excess of 4,000, peak 756c in the spectra 752 ofFIG. 17B has an intensity of about 3,400, and peak 764c in the spectra760 of FIG. 17C has an intensity of about 2,750; 4) at about the 587nanometer wavelength region, there is no peak in the spectra 744 of FIG.17A, but the intensity is about 500 (noise), there is no peak in thespectra 752 of FIG. 17B, but the intensity is about 490 (noise), andpeak 764d in the spectra 760 of FIG. 17C has an intensity of about3,000. These distinctions between the spectra 744, 752, and 760 showthat it is possible to distinguish between the various steps of a plasmarecipe, as well to evaluate the progression of a plasma recipe, throughan evaluation of the spectral pattern of the plasma in the chamber 36during the plasma recipe.

Exemplary Plasma Cleaning Operation Spectra With No Prior WetClean--FIGS. 18A-C

Representative spectra are presented in FIGS. 18A-C to illustrate howthe optical emissions of the plasma within the processing chamber 36changes over time during a plasma clean conducted without first doing awet clean of the chamber 36. FIG. 18A presents a spectra 770 of anexemplary plasma when the processing chamber 36 is in a dirty chambercondition and while plasma is present in the process chamber 36 withoutany product therein. FIG. 18B presents a spectra 774 of this sameexemplary plasma at an intermediate time of the plasma clean in whichthe dirty chamber condition has begun to be addressed by the plasmaclean. Finally, FIG. 18C presents a spectra 778 of this same exemplaryplasma at the end of the plasma clean at which time the interior of theprocessing chamber 36 is deemed to be in condition to return tocommercial production (e.g., to etch integrated circuit designs on aproduction wafer 18). This spectra 778 may be selected by the operatorof the facility implementing the wafer production system 2 as beingindicative of the chamber 36 being in proper condition for resumption ofproduction. However, it should be appreciated that there is notnecessarily a "bright line" as to when a chamber 474 is in condition toreturn to production. Therefore, the selection of the spectra 778 asbeing indicative of a "clean chamber condition" may be somewhatarbitrary.

Each of the spectra 770, 774, and 778 are characterized by a number ofpeaks 772, 776, and 780, respectively, of varying intensities at variouswavelengths. A comparison of the spectra 770, 774, and 778 reveals thattheir associated patterns are in fact different, including withoutlimitation as follows: 1) at about the 625 nanometer wavelength region,peak 772e in the spectra 770 of FIG. 18A has an intensity of about 500,peak 776e in the spectra 774 of FIG. 18B has an intensity of about 300,and there is no substantial peak in the spectra 778 of FIG. 18C; 2) atabout the 675 nanometer wavelength region, peak 772f in the spectra 770of FIG. 18A has an intensity of about 4,000, peak 776f in the spectra774 of FIG. 18B has an intensity of about 1,000, and there is nosubstantial peak in the spectra 778 of FIG. 18C; and 3) at about the 685nanometer wavelength region, peak 772g in the spectra 770 of FIG. 18Ahas an intensity of about 3,400, peak 776g in the spectra 774 of FIG.18B has an intensity of about 2,200, and peak 780g in the spectra 778 ofFIG. 18C has an intensity of about 700. These distinctions between thespectra 770, 774, and 778 show the progression of a plasma clean isevident in the spectral pattern of the plasma in the chamber 36 duringthe plasma clean.

More than one entry of a plasma cleaning may be required in the normalspectra subdirectory 288 depending upon a variety of factors. Forinstance, the spectral data of a plasma cleaning which is run after thechamber 36 has been running a first type of plasma recipe may lookdifferent than a plasma cleaning which is run after the chamber 36 hasbeen running a second type of plasma recipe which is different from thefirst type of plasma recipe.

Exemplary Plasma Cleaning Operation Spectra Conducted After WetClean--FIGS. 19A-C

Representative spectra of one plasma cleaning operation of the chamber36 after it has been wet cleaned are illustrated in FIGS. 19A-C. FIG.19A presents a spectra 1328 of the exemplary plasma in the processingchamber at the start of such a plasma cleaning of the chamber 36, whileFIG. 19B presents a spectra 1336 of the exemplary plasma at anintermediate point in such a plasma cleaning of the chamber 36, andwhile FIG. 19C presents a spectra 1344 of the exemplary plasma at theend of such a plasma cleaning of the chamber 36. Each of the spectra1328, 1336, and 1344 are characterized by a number of peaks 1332, 1340,and 1348, respectively, of varying intensities at various wavelengths. Acomparison of the spectra 1328, 1336, and 1344 reveals that theirrespective patterns are different, including without limitation asfollows: 1) at about the 625 nanometer wavelength region, peak 1332e inthe spectra 1328 of FIG. 19A has an intensity of about 600, peak 1340ein the spectra 1336 of FIG. 19B has intensity of about 500, and peak1348e in the spectra 1344 of FIG. 19C has an intensity of about 450; 2)at about the 668 nanometer wavelength region, peak 1332f in the spectra1328 of FIG. 19A has an intensity in excess of 4,000, peak 1340f in thespectra 1336 of FIG. 50B has intensity of about 1,000, and peak 1348f inthe spectra 1344 of FIG. 19C has an intensity of about 400; and 3) atabout the 685 nanometer wavelength region, peak 1332g in the spectra1328 of FIG. 19A has an intensity in excess of 3,400, peak 1340g in thespectra 1336 of FIG. 19B has intensity of about 2,300, and peak 1348g inthe spectra 1344 of FIG. 19C has an intensity of about 1,400. Thesedistinctions between the spectra 1328, 1336, and 1344 show that theprogression of a plasma cleaning operation is evident in the spectralpattern of the plasma in the chamber 36 during the plasma clean.

More than one entry of a plasma clean may be required in the normalspectra subdirectory 288 depending upon a variety of factors. Forinstance, the spectral data of a plasma clean run on a chamber 36 aftera wet clean may look different than a plasma clean that is run on a newchamber 36 which has not been wet cleaned. Moreover, the spectral dataof a plasma clean which is run after the chamber 36 has been running afirst type of plasma recipe may look different than a plasma clean whichis run after the chamber 36 has been running a second type of plasmarecipe which is different from the first type of plasma recipe.

Exemplary Conditioning Wafer Operation Spectra--FIGS. 20A-C

Representative spectra of a conditioning wafer operation are illustratedin FIGS. 20A-C. FIG. 20A presents a spectra 1288 of an exemplary plasmain the processing chamber 36 at the start of a conditioning waferoperation, FIG. 20B presents a spectra 1292 of an exemplary plasma at anintermediate point in the conditioning wafer operation, and FIG. 20Cpresents a spectra 1296 of an exemplary plasma at the end of theconditioning wafer operation. Each of the spectra 1288, 1292 and 1296are characterized by a number of peaks 1290, 1294, and 1298,respectively, of varying intensities at various wavelengths. Acomparison of the spectra 1288, 1292, and 1296 reveals that there arecertain differences in their respective patterns, including withoutlimitation as follows: 1) at about the 440 nanometer wavelength region,peak 1290a in the spectra 1288 of FIG. 20A has an intensity of about3,550, peak 1294a in the spectra 1292 of FIG. 20B has an intensity ofabout 3,750, and peak 1298a in the spectra 1296 of FIG. 20C has anintensity of about 4,000; 2) at about the 525 nanometer wavelengthregion, peak 1290b in the spectra 1288 of FIG. 20A has an intensity ofabout 2,800, peak 1294b in the spectra 1292 of FIG. 20B has an intensityof about 2,900, and peak 1298b in the spectra 1296 of FIG. 20C has anintensity of about 2,800; 3) at about the 595 nanometer wavelengthregion, peak 1290d in the spectra 1288 of FIG. 20A has an intensity ofabout 2,100, peak 1294d in the spectra 1292 of FIG. 20B has an intensityof about 2,150, and peak 1298d in the spectra 1296 of FIG. 20C has anintensity of about 2,125; 4) at about the 675 nanometer wavelengthregion, peak 1290e in the spectra 1288 of FIG. 20A has an intensity ofabout 600, peak 1294e in the spectra 1292 of FIG. 20B has an intensityof about 250, and there is no peak in the spectra 1296 of FIG. 20C; and5) at about the 685 nanometer wavelength region, peak 1290f in thespectra 1288 of FIG. 20A has an intensity of about 1,450, peak 1294f inthe spectra 1292 of FIG. 20B has an intensity of about 600, and there isno peak in the spectra 1296 of FIG. 20C. These distinctions between thespectra 1288, 1292, and 1296 show that the progression of a conditioningwafer operation is evident in the spectral pattern of the plasma in thechamber 36 during the operation.

More than one entry of a conditioning wafer operation may be required inthe normal spectra subdirectory 288 depending upon a variety of factors.For instance, the spectral data of a conditioning wafer operation whichis run after the chamber 36 has only been plasma cleaned may lookdifferent than the spectral data of a conditioning wafer operation whichis run in the chamber 36 after it has been both plasma cleaned, wetcleaned, and then again plasma cleaned. Moreover, the spectral data of aconditioning wafer operation run after the chamber 36 has been running afirst type of plasma recipe may look different than a conditioning waferoperation which is run after the chamber 36 has been running a secondtype of plasma recipe which is different from the first type of plasmarecipe.

Plasma Health Module 252--FIGS. 21-25

The current plasma process module 250 of FIGS. 7 and 32 is available formonitoring the health of any plasma process which is conducted withinthe processing chamber 36 first through a comparison of at least aportion of its spectral data with at least a portion of the spectraldata stored in the normal spectra subdirectory 288 (FIG. 9). Plasmarecipes (whether run on production wafers 18 or qualification wafers18), plasma cleans (with or without wet cleans), and conditioning waferoperations, as well as the health of any other plasma process, may eachbe evaluated through the plasma health module 252. How the plasma healthmodule 252 deals with the presence of having different categories ofplasma processes stored in the normal spectra subdirectory 288, as wellas in the abnormal spectra subdirectory 292 and the unknown spectrasubdirectory 296 which are also used in the plasma health evaluation ofa current plasma process being run in the chamber 36, is really a matterof preference. Some ways of dealing with the existence of multiplecategories of plasma processes may affect the speed of the evaluation bythe plasma health module 252 more than others. For instance, the plasmahealth module 252 may limit its comparison of the current plasma processto the same category or genus of plasma processes stored in the normalspectra directory 288 and abnormal spectra directory 292. Appropriate"identifying information" may be input into the plasma process genusfield 322h (FIG. 12A) associated with each plasma process stored in thenormal spectra subdirectory 288 and the plasma process genus field 333e(FIG. 12B) associated with each plasma process (or portion thereof)stored in the abnormal spectra subdirectory 292. Moreover, the currentplasma process to be conducted in the chamber 36 may be identified tothe plasma health module 252 in some manner. This may be accomplishedthrough the startup module 202 of FIG. 15 (e.g., through includingappropriate process category or genus identifying information in steps230, 234, 238, and 242 of the startup subroutine 203, which is passedonto step 236 of the subroutine 203, and which may be then passed on tothe plasma health module 252). Reducing the number of entries in thenormal spectra subdirectory 288 and abnormal spectra subdirectory 292which are compared with the current plasma process may and typicallywill increase the speed of evaluation of the health of the currentplasma process by the plasma health module 252. However, there may beadvantages to not imposing a plasma process category or genus matchcriterion when selecting data from the normal spectra subdirectory 288and/or abnormal spectra subdirectory 292 which is to be available forcomparison with the current plasma process.

Plasma health is also preferably evaluated by comparing opticalemissions from the current plasma process in the chamber 36 with theplasma spectra directory 284 over at least those wavelengths within thePreferred Optical Bandwidth based upon the Preferred Data Resolution,and using the Preferred Analytical Wavelength Resolution. However, insome cases some subset of the optical emissions data of the plasma inthe chamber 36 may be used to monitor the plasma health. One suchcircumstance is when processing speed is or potentially is an issue.There are a number of ways of selecting the amount of optical emissionsdata to monitor the health of a plasma process. The data within theabnormal spectra subdirectory 292 of FIG. 9 may be used to generate thesubset of data which may be reviewed for purposes of monitoring theplasma health. For instance, the plasma health evaluation may beconducted over optical emissions segments which include thosewavelengths which are indicative of errors which occurred in processespreviously conducted within the chamber 36. One alternative is to definean optical emissions segment ±25 nanometers on each side of eachwavelength of a spectra in the abnormal spectra subdirectory 292 whichis indicative of an error from a previous plasma process. For instance,if errors from previous runs are reflected at the 325, 425, and 575wavelengths, the plasma health may be evaluated by looking at each ofthe 300-350, 400-450, and 550-600 nanometer region. A smaller opticalemissions segment for monitoring plasma health may also be selected bydefining a range which includes each of those wavelengths which areindicative of errors from the abnormal spectra subdirectory 292. Forinstance, if errors from previous runs are reflected at the 325, 425,and 575 wavelengths, the plasma health may be evaluated by looking atthe wavelength region from about 325 nanometers to about 575 nanometers.It may be desirable to include a "buffer" on each of the endpoints ofthis range as well (e.g., extend by about 25 nanometers on each end ofthe range). The above may be further limited by limiting the plasmahealth evaluation to those optical emissions segments which include onlyerrors from the same type of plasma process which is to be run in thechamber 36 (e.g., same plasma recipe). Finally, information on endpointof the plasma process or discrete portion thereof may be used to definethe wavelengths to be evaluated in relation to plasma health. As will bediscussed in more detail below in relation to the endpoint detectionmodule 1200 and FIG. 52, endpoint may be called based upon a change atone or more specific wavelengths. Plasma health may be evaluated bylooking at a ±25 nanometer region around each wavelength which is usedto call endpoint. Notwithstanding the foregoing, plasma health should beevaluated over at least a 50 nanometer wavelength in which data has beencollected at the Preferred Data Resolution, and again is preferablyundertaken using the Preferred Optical Bandwidth.

Plasma Health Subroutine 253--FIG. 21

One embodiment of a subroutine is illustrated in FIG. 21 which may beused by the plasma health module 252 to evaluate whether a currentplasma process is proceeding in accordance with at least one plasmaprocess stored in the normal spectra subdirectory 288 of FIG. 9 (e.g.,indicative of a "healthy" plasma). Summarily, spectral data is takenduring and more preferably throughout the entirety of the execution ofthe current plasma process which is being run within the processingchamber 36. Consideration should be given to the first part of a plasmaprocess being somewhat unstable. Spectral data from the current plasmaprocess is first compared against the normal spectra subdirectory 288 todetermine if the current plasma process "matches" any plasma processstored within the normal spectra subdirectory 288. As long as thecurrent plasma process "matches" at least one plasma process stored inthe normal spectra subdirectory 288, the current plasma process ischaracterized as being "normal" or "healthy" and the plasma healthsubroutine 253 will continue to limit its search for "matching" spectrato the normal spectra subdirectory 288. However, oftentimes there is anerror or aberration during a plasma process which may have some type ofadverse effect on the desired end result of the plasma process, and thisshould be identifiable from the spectra of the plasma in the chamber 36.

During an error or aberration in a plasma process currently being run,the spectra of the plasma in the chamber 36 should no longer "match" anyplasma process stored in the normal spectra subdirectory 288. The plasmahealth subroutine 253 will then discontinue its search of the normalspectra subdirectory 288 for evaluating the current plasma process andstart comparing the current plasma process with the abnormal spectrasubdirectory 292 of FIG. 9. Errors or aberrations in plasma processeswhich have been encountered before by the plasma health subroutine 253on this same chamber 36, and which have had their corresponding cause orcauses identified, are recorded in the abnormal spectra subdirectory292. Actions which may be initiated if spectral data of the currentplasma process "matches" at least one spectra in the abnormal spectrasubdirectory 292 range from issuing an appropriate alert to addressingone or more process control features of the wafer production system 2 asdiscussed above in relation to the process alert subroutine 432 of FIG.14.

All of the data in the normal spectra subdirectory 288 and the abnormalspectra subdirectory 292 is obtained from the processing chamber 36 onwhich the plasma health module 252 is being used to evaluate any plasmaprocess currently being run or which was run in this very same chamber36. Building of the library of information for the normal spectrasubdirectory 288 and abnormal spectra subdirectory 292 takes time toallow the plasma health subroutine 253 to "learn" from the chamber 36and the plasma processes being run therein. Circumstances will thereforelikely arise where the spectral data of the plasma from the currentplasma process cannot be found in either the normal spectra subdirectory288 or the abnormal spectra subdirectory 296 by the plasma healthsubroutine 253. Information of this type is stored for the subroutine253 in the unknown spectra subdirectory 296 of FIG. 9. It will likelyremain an "unknown condition" until the spectral data can be properlyanalyzed and the "cause" identified, at which time the relevant spectraldata may be transferred to either the normal spectra subdirectory 288 orthe abnormal spectra subdirectory 292 to upgrade the plasma healthsubroutine's 253 knowledge of the processing chamber 36 and itsassociated plasma processes.

Specifics of the plasma health subroutine 253 will now be addressed inthe case where the plasma process is a plasma recipe being run on wafers18 in the chamber 36. An exemplary general procedure for running aplasma recipe on wafers 18 is as follows. First, a cassette 6 having aplurality of production wafers 18 therein, as well as possibly one ormore qualification wafers, is transferred into one of the load lockchambers 28 (FIG. 1). The wafer handling assembly 44 will retrieve oneof the wafers 18 from the cassette 6 and transport the same into theprocessing chamber 36. At this time, the plasma in the chamber 36 isoff. The chamber 36 is sealed and the plasma is ignited to run a plasmarecipe on the wafer 18. Typical practice is to run the same plasmarecipe on the entire cassette 6. After the completion of the plasmarecipe on the first wafer 18, the plasma is turned off, the chamber 36is opened, and the wafer handling assembly 44 retrieves the wafer 18from the chamber 36 and provides the same back to its corresponding slotin the cassette 6. Once all of the wafers 18 of the cassette 6 have beenprocessed in this manner (usually 1-3 qualification wafers are used fora cassette 6 having 24 wafers 18 and may be included anywhere within thecassette 6), the cassette 6 may be removed from the load lock chamber 28and replaced with another cassette 6 of wafers 18. The qualificationwafers 18 from the plasma processed cassette 6 may then be tested(destructively or non-destructively), while semiconductor devices may beformed from the production wafers 18.

Plasma processes, whether are run on qualification or production wafers18, in the processing chamber 36 are evaluated by the plasma healthmodule 252. Usually no more than a 1 minute time lapse exists betweenthe time one production wafer 18 is removed from the processing chamber36 and the time the plasma recipe is initiated on the next productionwafer 18 which is loaded into the chamber 36. The plasma health module252 is able to complete its evaluation of a plasma recipe which was runon a production wafer 18 before the plasma recipe is initiated on thenext production wafer 18 since the plasma health module 252 effectivelyrelies on pure pattern recognition techniques, and not chemical analysisor chemical species identification techniques. Moreover and as will bediscussed in more detail below, the plasma health module 252 is able tonot only determine the identify of the plasma process, but to determinethat the plasma process is being run on a qualification wafer 18 versusa production wafer 18.

Data which relates to the current plasma process being run on product inthe processing chamber 36 at the current time t_(c) is obtained forevaluation by the plasma health subroutine 253 of FIG. 21 throughexecution of step 254. Although step 254 is referenced in FIG. 21 inrelation to merely a "spectra" or optical emissions data, as notedabove, other types of data may be taken at/associated with this time aswell (e.g., the time into the plasma recipe at which the associatedspectra was obtained from the chamber 36). A comparison is then made atstep 258 of the plasma health subroutine 253 between the spectra of thecurrent plasma process obtained at step 254 (current plasma process) andthe relevant spectra from the normal spectra subdirectory 288 (storedplasma process). For facilitating the initial understanding of how thehealth of a plasma process may be evaluated by the process health module252, the normal spectra directory 288 will hereafter be described ashaving only a single plasma process stored therein ("Recipe A"). How thehealth of a current plasma process may be handled by the plasma healthmodule 252 in the situation where multiple plasma processes are storedin the normal spectra subdirectory 288 is addressed in the discussion ofthe plasma health/process recognition subroutines 790, 852, and 924presented below in relation to FIGS. 22-24.

Step 258 of the plasma health subroutine 253 calls the patternrecognition module 370 of FIG. 13 to undertake a comparative analysisbetween the spectra of the plasma in the chamber 36 at the current timet_(c) and the relevant spectra of Recipe A from the normal spectrasubdirectory 288. This is affected by step 258 of the subroutine 253setting the Target Directory used by the pattern recognition module 370to the normal spectra subdirectory 288. Only the normal spectrasubdirectory 288 is then searched by the pattern recognition module 370at this time, through execution of step 258 of the plasma healthsubroutine 253, to determine if there is a "match" between the currentspectra at the current time t_(c) and Recipe A as stored in the normalspectra subdirectory 288. Which spectra of Recipe A is actually comparedwith the current spectra in this instance is addressed below after thediscussion of the loop 190 of the subroutine 253 is completed.

The pattern recognition module 370 of FIG. 13 returns control of theplasma monitoring operation back to the plasma health subroutine 253 ofFIG. 21 after the pattern recognition module 370 has determined whetherthere is a "match" between the spectra at the current time t_(c) (fromstep 254 of the plasma health subroutine 253) and the relevant spectraof Recipe A from the normal spectra subdirectory 288 in the subjectexample. The result ("match" or "no match") of the analysis by thepattern recognition module 370 is actually provided to step 260 of theplasma health subroutine 253 of FIG. 21. If the current spectra at thecurrent time t_(c) was a "match" with the relevant spectra of Recipe A,the evaluation by the plasma health subroutine 253 will continue inrelation to the normal subdirectory 288. In this regard, the plasmahealth subroutine 253 inquires at step 261 as to whether the currentplasma process being conducted in the processing chamber 36 has beenterminated, or more accurately if there are any more spectra from thesubject current plasma process being run in the chamber 36 to beevaluated by the subroutine 253. Other information on the subjectcurrent plasma process may be provided through execution of step 194 ofthe plasma health subroutine 253 which calls other sub-modules of thecurrent plasma process module 250 as will be discussed in more detailbelow (e.g., to access a chamber condition evaluation function, toaccess an endpoint determination function).

Additional optical emissions data on the current plasma process forevaluation by the plasma health subroutine 253 is made available throughexecution of step 278. At step 278 the "clock" of the subroutine 253 iseffectively reset. Step 278 of the subroutine 253 more specificallyprovides for adjustment of the "clock" by a predetermined increment "n"to thereby increase the current time t_(c) by an increment of "n." Themagnitude of "n" defines that portion of the collected data which willbe analyzed. All of the data may be analyzed, or only a portion thereof(e.g., only every other "piece" of optical emissions data may actuallybe analyzed). Hereafter, this concept will be referred to as theAnalytical Time Resolution. In one embodiment, the Analytical TimeResolution in relation to plasma health is at least at every 1 second,and more preferably at least at every 300 milliseconds. The plasmahealth subroutine 253 then returns to step 254 where the next spectra ofthe plasma in the processing chamber 36 from the execution of thecurrent plasma process is obtained for the subroutine 253 at the newcurrent time t_(c) such that the same may be evaluated in accordancewith the foregoing.

There are a number of ways to define what is the "relevant spectra" of aplasma process stored in the normal spectra subdirectory 288 forcomparison with the current spectra of the plasma in the chamber 36 atthe current time t_(c) through the plasma health subroutine 253.Relevance may be time dependent and will hereafter be referred to as a"time dependency requirement." In the subject example where the onlyplasma process stored in the normal spectra subdirectory 288 is RecipeA, the relevant spectra of Recipe A to be compared with the spectra ofthe plasma in the chamber 36 at the current time t_(c) would be limitedto that spectra for Recipe A which is associated with this same currenttime t_(c) if a time dependency requirement was used. That is, thespectra of the plasma in the chamber 36 during the current plasmaprocess at time t₁ would be compared with Recipe A's spectra which isassociated with the same time t₁ through execution of step 258 of theplasma health subroutine 253, the spectra of the plasma in the chamber36 during the current plasma process at time t₂ would be compared withthe Recipe A's spectra which is associated with the same time t₂ throughexecution of step 258 of the subroutine 253, and so forth. This timedependency requirement for determining what is the "relevant spectra"may be used regardless of which subdirectory of the plasma spectradirectory 284 is being "searched" by the pattern recognition module 370.

In theory, a time dependency requirement is an acceptable way toevaluate whether a current plasma process is proceeding in accordancewith any one or more plasma processes stored in the normal spectrasubdirectory 288. From a practical standpoint this is not necessarilythe case. Variations throughout the wafers 18 in a given wafer cassette6 on which the same plasma recipe is typically run may affect the amountof time required to complete one or more of the plasma steps of thecurrent plasma recipe being run in the chamber 36. For instance, thethickness of a certain layer to be etched away by a certain step of theplasma recipe may vary from wafer 18 to wafer 18 within an acceptabletolerance. Conditions within the chamber 36 may also have an effect onthe amount of time required to reach the endpoint of one or more plasmasteps of a given plasma recipe or any other plasma process for thatmatter. For instance, as the interior of the chamber 36 ages by theformation of deposits within the interior, by the etching away ofmaterials from the interior, or both, the performance of the chamber 36may change. Changing the performance of the chamber 36 may change theamount of time required to reach the endpoint of one or more steps of agiven plasma recipe. Other factors may affect timing issues associatedwith other types of plasma processes run in the chamber 36. Failing toaccount for these types of factors will result in the plasma healthsubroutine 253 issuing false alarms, or more specifically an indicationthat a current plasma process does not conform with at least one plasmaprocess stored in the normal spectra subdirectory 288 when such is notthe case.

Alternatives to the time dependency requirements exist for determiningwhat is the "relevant spectra" of a given plasma process stored in thenormal spectra subdirectory 288 for comparison with the spectra of theplasma in the chamber 36 at the current time t_(c) from the currentplasma process. "Relevant" in the context of the plasma healthsubroutine 253, and in fact for each sub-module of the current plasmaprocess module 250, may simply be whether the current plasma processbeing run in the chamber 36 is progressing in a manner consistent withat least one of the plasma processes stored in the normal spectrasubdirectory 288, although not necessarily at the same speed andtherefore not being time dependent. Hereafter this will be referred toas a "progression dependency requirement" and is exemplified by thefollowing. The first spectra obtained for the plasma health subroutine253 at the current time t₁ is compared with one or more spectra ofRecipe A in the normal spectra subdirectory 288 in the subject example.The spectra of Recipe A which matched the spectra of the plasma in thechamber 36 at the current time t₁, and which has the earliest timeassociated therewith, is identified as the current status spectra ofRecipe A. This accounts for the possible, although likely improbable,situation where a spectra at time t₁ in a given plasma process issubstantially the same as a spectra at, for instance, time t₁₀₀ in thissame plasma process. The next spectra obtained for the plasma healthsubroutine 253, or the spectra at time t₂ in the example, is firstcompared with this same current status spectra of Recipe A in the normalspectra subdirectory 288. If the current spectra at the current time t₂still matches this current status spectra of Recipe A, the currentstatus spectra of Recipe A remains unchanged. However, if the spectra ofthe plasma in the chamber 36 from the current plasma recipe being run onproduct in the chamber 36 at the current time t₂ does not match thecurrent status spectra of Recipe A, the pattern recognition module 370will look to see if this current spectra matches the spectra of Recipe Awhich follows (in time) the current status spectra in Recipe A. A"match" between the current spectra of the plasma in the processingchamber 36 at the current time t_(c) and the spectra of Recipe A whichfollows the current status spectra means that the current plasma processis progressing accordingly, and this later in time "matching spectra" inRecipe A is now the current status spectra of Recipe A. The foregoinglogic will continue to repeated so long as the current plasma process isprogressing in accordance with Recipe A of the normal spectrasubdirectory 288. This progression dependency requirement may be usedregardless of which subdirectory of the plasma spectra directory 284 isbeing searched by the pattern recognition module 370. Moreover, thelogic may be that the current spectra is first checked against the nextspectra following (in time) the current status spectra, and then backagainst the current status spectra only if there is not match forpurposes of determining if the process is progressing (e.g., assumeprogression at the same rate and only look back if necessary).

The loop 190 defined by steps 254, 258, 260, 261, and 278 of the plasmahealth subroutine 253 will continue to be re-executed until one of twoevents occurs. One event which will cause the plasma health subroutine253 to exit the loop 190 is when all of the spectral data on the currentplasma process has been evaluated by the subroutine 253 in accordancewith the foregoing. That is, the entirety of the current plasma processrun in the processing chamber 36 proceeded in accordance with at leastone of the plasma processes recorded in the normal spectra subdirectory288 ("at least one" referring to the fact that more than one entry of agiven plasma process may be included in the normal spectra subdirectory288), or in the subject example Recipe A. Control of the plasmamonitoring operations is then transferred from the plasma healthsubroutine 253 back to, for instance, the startup module 202 of FIG. 15through execution of step 279 of the plasma health subroutine 253. Itshould be noted that the results of "normal" runs may be recorded in a"normal run" log file. Data such as that presented in FIG. 12A may beincluded in this "normal run" log file and will provide a historicalrecord of the subject plasma process. If data storage space is an issue,the spectral data may be omitted from the historical record although itis desirable to retain this data. Moreover, this historical data neednot be stored for access by the current plasma process module 250. Forinstance, the historical data may be stored on a network associated withthe wafer production system 2 or any other data storage area.

The plasma health subroutine 253 may also exit the loop 190 (theevaluation of the current spectra at the current time t_(c) in relationto the normal spectra subdirectory 288 of FIG. 9) when this currentspectra is no longer a "match" with any plasma process stored in thenormal spectra subdirectory 288. This would be the case when at somepoint in time the current plasma recipe being run on product within theprocessing chamber 36 was not a "match" with Recipe A of the normalspectra subdirectory 288 in the subject example. The results of thepattern recognition module 370 of FIG. 13 provided back to step 260 ofthe plasma health subroutine 253 in this case would cause the subroutine253 to proceed from step 260 to step 266.

Step 266 of the plasma health subroutine 253 calls the patternrecognition module 370 of FIG. 13 to undertake a comparative analysisbetween the spectra of the plasma in the chamber 36 at the current timet_(c) and the relevant spectra of the abnormal spectra subdirectory 292.This is accomplished by step 266 of the subroutine 253 setting theTarget Directory used by the pattern recognition module 370 to theabnormal spectra subdirectory 292. Only the abnormal spectrasubdirectory 292 is then searched by the pattern recognition module 370through execution of step 266 to determine if there is a "match" betweenthe current spectra of the plasma in the chamber 36 at the current timet_(c) and the relevant spectra stored in the abnormal spectrasubdirectory 292.

A number of options exist in relation to which spectra of the abnormalspectra subdirectory 292 of FIG. 9 are actually compared with thecurrent spectra of the plasma in the processing chamber 36 at thecurrent time t_(c) using the above-described analysis provided by thepattern recognition module 370. Each spectra stored within the abnormalspectra subdirectory 292 may and preferably does have a time associatedtherewith, which is the time into the plasma process in which thespectra was obtained from within the chamber 36 (i.e., its correspondingt_(c)). The search of the abnormal spectra subdirectory 292 for"matches" by the pattern recognition module 370 may be limited to thosespectra which were recorded at the same current time t_(c) or within apredetermined amount of time on each side of the subject current timet_(c) (e.g., ±"x" seconds of the subject current time t_(c)). Forexample, if the current spectra was obtained 20 seconds into a plasmaprocess being run in the processing chamber 36, the point-by-pointanalysis embodied by step 386 of the pattern recognition subroutine 374of FIG. 13 may be performed in relation to only those spectra within theabnormal spectra subdirectory 292 which were also recorded at the same20 second time period or within ±10 seconds (or any other desiredamount) of this time period.

Another subset of the abnormal spectra subdirectory 292 which may beused as a refining search criteria is the plasma process category/genus,or even the plasma process type or species within a plasma processcategory/genus having multiple types/species of plasma processes (e.g.,a specific type of plasma recipe). That is, only those spectra in theabnormal spectra subdirectory 292 which are associated with a plasmaprocess which is at least possibly the same as that currently being runon product within the processing chamber 36 will be analyzed by thepattern recognition module 370 using a plasma process criterion."Potential" matching processes is used in this situation because at thetime of the error in the current plasma process, the plasma healthmodule 252 may not have narrowed down the identification of the currentplasma process to a single plasma process within the normal spectrasubdirectory 288. How the plasma health module 252 may identify acurrent plasma process being run on product in the processing chamber 36is addressed below in relation to the plasma health/process recognitionsubroutines 790, 852, and 924 of FIGS. 22-24.

The plasma step of a plasma process may also be used as a refiningsearch criterion for which spectra of the abnormal spectra subdirectory292 are analyzed by the pattern recognition module 370. That is, onlythose spectra in the abnormal spectra subdirectory 292 which areassociated with a plasma step of a multiple step plasma process which isstill possibly a match with a current plasma step being run within theprocessing chamber 36 will be analyzed by the pattern recognition module370 in this case. "Potential" is used in relation to matching plasmasteps of plasma processes in this situation because at the time of theerror in the current plasma process, the plasma health module 252 maynot have narrowed down the identification of the current plasma step andprocess to a single plasma step of a single plasma process within thenormal spectra subdirectory 288. How the plasma health module 252 mayidentify a current plasma step of a current plasma process being run inthe processing chamber 36 is through the plasma health/process steprecognition subroutine 972 which will be discussed below in relation toFIG. 25.

Any combination of the foregoing may be used as initial search criteriato initially refine the search of the abnormal spectra subdirectory 292.Finally, no refining search criteria need be used. That is, the searchof the abnormal spectra subdirectory 292 for "matches" may compare thecurrent spectra at the current time t_(c) with each spectra within theabnormal spectra subdirectory 292, thereby removing both the timeelement and plasma process category/plasma process type within a givenplasma process category/plasma step element as required "initial match"criteria.

The pattern recognition module 370 returns control of the plasmamonitoring operation back to the plasma health subroutine 253 of FIG. 21after the pattern recognition module 370 has determined whether there isa "match" between the spectra of the plasma in the chamber 36 at thecurrent time t_(c) (from step 254 of the plasma health subroutine 253)and the relevant spectra from the abnormal spectra subdirectory 292. Theresult ("match" or "no match") of the analysis by the patternrecognition module 370 is provided to step 276 of the plasma healthsubroutine 253 of FIG. 21. If the current spectra of the plasma in theprocessing chamber 36 at the current time t_(c) was a "match" with atleast one spectra in the abnormal spectra subdirectory 292, the plasmahealth subroutine 253 effectively takes two actions and these actionsmay be undertaken in any order, including simultaneously. One of theseactions is that the plasma health subroutine 253 will proceed to step274 which calls the process alert module 428 which was discussed abovein relation to FIG. 14. Generally, alerts may be issued as to theidentification of the abnormal condition, control of the waferproduction system 2 may be addressed, or both through the process alertmodule 428. Another action which is taken by the plasma healthsubroutine 253 in this type of case is to record data of the remainderof the plasma process in an "abnormal run" log file for historicalpurposes.

At a minimum, spectral data is recorded in an "abnormal run" log filethrough execution of step 264 for the current time t_(c) (the firstspectra which did not "match" any relevant plasma process stored in thesubdirectory 288, but which did "match" at least one entry in theabnormal spectra subdirectory 292). Proceeding from step 264 to step 265of the plasma health subroutine 253 of FIG. 21, a determination is madeas to the status of the current plasma process. Any termination of theplasma process, or more accurately recordation of data on the remainderof the process, will cause the subroutine 253 to proceed to step 267where control of the plasma monitoring operations may be returned to,for instance, the startup module 202 of FIG. 15. Continuation of theplasma process after the error is identified will cause the subroutine253 to proceed from step 265 to step 268 where the current time t_(c) isincreased by a factor of "n" such that another spectra of the plasma inthe chamber 36 can be obtained for the subroutine 253 at this newcurrent time t_(c) through step 272 for recordation in the "abnormalrun" log file. The magnitude of "n" may be the Preferred Analytical TimeResolution. Steps 264, 265, 268, and 272 will continue to be repeated inthe described manner to continue to record data in the "abnormal run"log file until the current plasma process is terminated, at which timethe subroutine 253 will exit at step 267 as described.

Circumstances will be encountered where the current spectra of theplasma in the processing chamber 36 at the current time t_(c) will not"match" any plasma process stored in the normal spectra subdirectory288, and further where this current spectra will not "match" anyrelevant spectra stored in the abnormal spectra subdirectory 292. Thisis referred to herein as an "unknown condition." The plasma healthsubroutine 253 of FIG. 21 handles this type of situation by exiting step276 to where the subroutine 253 effectively takes two actions, and theseactions may be undertaken in any order and including simultaneously. Oneof these actions is that the plasma health subroutine 253 will executestep 256 which calls the process alert module 428 discussed above inrelation to FIG. 14. Generally, alerts may be issued as to the existenceof the unknown condition, control of the wafer production system 2 maybe addressed, or both through the process alert module 428. Another"action" which is taken by the plasma health subroutine 253 in this typeof case is to record data of the remainder of the plasma process in theunknown spectra subdirectory 296.

At a minimum, spectral data is recorded in the unknown spectrasubdirectory 296 through execution of step 270 for the current timet_(c) (the first spectra which did not "match" any relevant plasmaprocess stored in the normal spectra subdirectory 288, and which alsodid not "match" any relevant entry in the abnormal spectra subdirectory292). Proceeding from step 270 to step 283 of the plasma healthsubroutine 253, a determination is made if the current plasma processhas been terminated (e.g., is the plasma "off" in the chamber 36). Anytermination of the plasma process will cause the subroutine 253 toproceed to step 281 where control of the plasma monitoring operationsmay be returned to, for instance, the startup module 202 of FIG. 15.Continuation of the plasma process after the unknown condition isencountered will cause the subroutine 253 to proceed from step 283 tostep 280 where the current time t_(c) is increased by a factor of "n"(e.g., Preferred Data Collection Time Resolution) such that anotherspectra of the plasma in the chamber 36 can be obtained for thesubroutine 253 at this new current time t_(c) through step 282 forrecordation in the unknown spectra subdirectory 296. Steps 270, 283,280, and 282 will continue to be repeated in the described manner untilthe current plasma process is terminated or until data on the remainderof the process has been recorded in the subdirectory 296, at which timethe subroutine 253 will exit at step 281 as described.

Plasma process runs which are recorded in the unknown spectrasubdirectory 296 are typically subsequently analayzed to attempt toidentify the cause of the unknown condition as noted above. If theunknown condition actually turns out to be a new plasma process, thedata recorded in the unknown spectra subdirectory 296 may be transferredto the normal spectra subdirectory 288. New spectral patterns from thisnew plasma process will then be available to assess further runnings ofplasma processes on this same processing chamber 36. If the unknowncondition turns out to be an error with an associated cause, some or allof the data from the subject run recorded in the unknown spectrasubdirectory 296 may be transferred to the abnormal spectra subdirectory292. At least one new spectral pattern which is representative of thenewly identified error condition will then be available to assessfurther runnings of plasma processes on this same processing chamber 36through the plasma health module 252.

Plasma Health/Process Recognition Subroutine 790--FIG. 22

Another embodiment of a subroutine which may be used by the plasmahealth module 252 is presented in FIG. 22. Not only is the health orcondition of the plasma assessed by the subroutine 790 in FIG. 22, butthe particular plasma process which is being run in the chamber 36 isalso identified. That is, the subroutine 790 is able to determine theidentify of the plasma process (e.g., to distinguish between differenttypes of plasma recipes, to distinguish between the same plasma reciperun on a production wafer 18 and a qualification wafer 18, etc).Consequently, the subroutine 790 is characterized as a plasmahealth/process recognition subroutine 790. The plasma health/processrecognition subroutine 790 also presents one way in which a currentplasma process being run in the subject chamber 36 may be evaluatedagainst multiple plasma processes stored in the normal spectrasubdirectory 288 of FIG. 9. These very same principles may beimplemented in the plasma health subroutine 253 of FIG. 21.

A number of prerequisites are addressed before the plasma health/processrecognition subroutine 790 actually initiates its analysis of thecurrent plasma process being run in the processing chamber 36. The orderin which these steps are executed is not important to the presentinvention. Initialization of the plasma health/process recognitionsubroutine 790 includes setting the Target Directory associated with thepattern recognition module 370 of FIG. 13 to the normal spectradirectory 288 of FIG. 9 at step 796 of the subroutine 790. Generally,the pattern recognition module 370 is used by the subroutine 790 tocompare the pattern of a "run spectra" (i.e., a spectra of the plasmafrom the processing chamber 36 during a plasma process being run in theprocessing chamber 36) with the relevant spectra of the plasma processesstored in the normal spectra subdirectory 288.

Preparation for the analysis of the current plasma process being run inthe chamber 36 by the plasma health/process recognition subroutine 790also requires execution of step 816 which "calls up" or "flags" thefirst plasma process in the normal spectra subdirectory 288 which is tobe compared with the current plasma process by the subroutine 790. Thelogic of the subroutine 790 is to compare the current plasma processbeing run in the processing chamber 36 with only one plasma processstored in the normal spectra subdirectory 288 at a time. That is, thesubroutine 790 will first compare the current plasma process withProcess A in the normal spectra subdirectory 288. If the current plasmaprocess deviates from Process A, then the subroutine 790 will comparethe entirety of the subject current plasma process with Process B in thenormal spectra subdirectory 288. Only if the current plasma processdeviates from Process B will other plasma processes stored in the normalspectra subdirectory 288 be compared one at a time with the currentplasma process by the plasma health/process recognition subroutine 790.As in the case of the plasma health subroutine 253 discussed above inrelation to FIG. 21, the plasma health/process recognition subroutine790 may be configured to make all plasma processes stored in the normalspectra subdirectory 292 available for comparison with the currentplasma process, or the above-noted refining criterion/criteria may beused.

The first spectra of the plasma in the processing chamber 36 obtainedfor the plasma health/process recognition subroutine 790 is throughexecution of step 794 and which is also part of the initialization ofthe subroutine 790. This spectra is associated with the time t_(o)(hereafter "start time t₀ "), and is stored along with each spectraobtained for the subroutine 790 until its analysis is completed. Anyfailure to retain the spectra of the current plasma process would notallow the subroutine 790 to use its "one process at a time" comparativelogic.

Assume that the first plasma process stored in the normal spectrasubdirectory 292 to be compared with the current plasma process beingrun in the chamber 36 is Process A. The first step of the subroutine 790which is repeated for each plasma process evaluated by the subroutine790 is step 798 where a current time t_(c) variable is introduced, andfurther where this current time t_(c) is set equal to the starting timet₀. Comparison of the current plasma process being run in the processingchamber 36 with the data from step 816 is undertaken at step 800 wherethe plasma health/process recognition subroutine 790 is directed toproceed to the pattern recognition module 370 of FIG. 13. An analysis ofthe spectra of the plasma from the processing chamber 36 at the currenttime t_(c) is undertaken at step 800 to determine if the pattern of thiscurrent spectra is a "match" with the relevant spectra of Process A ofthe normal spectra subdirectory 288. As discussed above in relation toFIG. 13, the "match determination" is effectively a comparison of thepatterns of the two noted spectra to determine if the pattern of thecurrent spectra is sufficiently similar to the pattern of the relevantspectra of Process A from the normal spectra subdirectory 288 to beconsidered a "match" therewith. "Relevance" in terms of which spectra ofa given plasma process from the normal spectra subdirectory 288 iscompared with the spectra of the plasma in the chamber 36 at the currenttime t_(c) by the subroutine 790 may be determined in accordance witheither the time dependency requirement or the progression dependencyrequirement discussed above in relation to the plasma health subroutine253 of FIG. 21.

The results of the analysis from step 800 are evaluated at step 812 ofthe plasma health/process recognition subroutine 790. If the spectra ofthe plasma in the processing chamber 36 associated with the currentplasma process at the current time t_(c) is a "match" with the relevantspectra of Process A in the normal spectra subdirectory 288, thesubroutine 790 proceeds to step 802 where the results are displayed. Forinstance, an indication may be provided to operations personnel on thedisplay 130 (FIG. 6), or by any of the other methods described above,that the plasma health/process recognition subroutine 790 has determinedthat the current plasma process being run in the processing chamber 36corresponds, through the current time t_(c), with Process A. It may beinaccurate and therefore inadvisable at this point in time to indicatethat the plasma process currently being run in the processing chamber 36is definitively Process A. Specifically, the comparison of the currentplasma process with the normal spectra subdirectory 288 up to this timehas been limited to Process A. The spectra of the plasma in the chamber36 up through the current time t_(c) could in fact also "match" therelevant spectra of one or more other plasma processes stored in thenormal spectra subdirectory 288. However, this has not yet beendetermined as the logic employed by the plasma health/processrecognition subroutine 790 is to evaluate the current plasma processbeing run in the processing chamber 36 against only a single plasmaprocess in the normal spectra subdirectory 288 at a time. Therefore, atthis time all that should be said is that the current plasma process ispotentially Process A.

The status of the evaluation of the current plasma process is checked atstep 806 of the plasma health/process recognition subroutine 790.Execution of step 806 determines if all of the data from the currentplasma process has been evaluated by the subroutine 790 (e.g., has allthe data obtained up until the plasma goes "off" been evaluated). Anycontinuation of the current plasma process or a failure to have examinedall of its optical emissions data will cause the plasma health/processrecognition subroutine 790 to proceed to step 804 which causes thecurrent time t_(c) to be adjusted by an increment of "n." The magnitudeof "n" defines the Analytical Time Resolution, and preferably thePreferred Analytical Time Resolution is implemented. For instance, ifthe start time t₀ was set at one second (where the initial spectrareading was obtained for the subroutine 790 at step 794) and thevariable "n" was set at two seconds, the current time t_(c) upon exitingstep 804 would be 3 seconds. The spectra at this new current time t_(c)from the processing chamber 36 is then obtained for the subroutine 790at step 808, and the subroutine 790 returns to step 800 where thepattern of this new spectra is compared with the pattern of the relevantspectra of Recipe A to determine if they "match" in accordance with theforegoing.

Steps 800, 812, 802, 806, 804, and 808 define a loop 818 which continuesto be executed to compare the current plasma process being run in theprocessing chamber 36 with one of the plasma processes stored in thenormal spectra subdirectory 288 (Process A in the subject example) untilone of two conditions exists. One of these conditions is where thecurrent plasma process has been completed and "matched" an entire plasmaprocess stored in the normal spectra subdirectory 288. In this case, thesubroutine will exit from step 806 to step 810. Control of the plasmamonitoring operations may be returned by step 810 to, for instance, thestartup module 202 of FIG. 15.

Another condition where the subroutine 790 will exit the loop 818 iswhen the spectra of the plasma in the processing chamber 36 at the thencurrent time t_(c) does not "match" with the relevant spectra of theplasma process stored in the normal spectra subdirectory 288 currentlybeing used by the plasma health/process recognition subroutine 790(Process A in the subject example). In this case, the subroutine 790will exit from step 812 to step 814. Step 814 basically inquires as towhether each plasma process stored in the normal spectra subdirectory288 has been compared with the current plasma process by the subroutine790 through the loop 818. If at least one plasma process stored in thenormal spectra subdirectory 288 has not yet been used as a comparativestandard for the current plasma process after the subroutine 790 hasexited the loop 818, the plasma health/process recognition subroutine790 will proceed from step 814 to step 822 where data on the next plasmaprocess stored in the normal spectra subdirectory 288 is recalled insome manner for use by the subroutine 790. This data on a plasma processstored in the normal spectra subdirectory 288 is recalled for evaluationby the subroutine 790 against the current plasma process from the timet₀ through the latest current time t_(c) (i.e., from the very beginningof this plasma process). That is, the subroutine 790 returns to step 798from step 822 where the current time t_(c) is returned to the start timet₀, and the loop 818 of the subroutine 790 is entered to evaluate thecurrent plasma process against the next plasma process stored in thenormal spectra subdirectory 288 in the above-described manner.

There will be cases where the current plasma process being run in thechamber 36 does not "match" any plasma process stored in the normalspectra subdirectory 288. In this case the plasma health/processrecognition subroutine 790 will exit step 814 and proceed to step 820.The protocol of step 820 generally directs the plasma health/processrecognition subroutine 790 to determine if the current plasma recipe hasencountered a known error/aberration which is stored in the abnormalspectra subdirectory 292. Therefore, the plasma health/processrecognition subroutine 790 may include the portion of the plasma healthsubroutine 253 of FIG. 21 which pertains to the abnormal spectrasubdirectory 292 and the unknown spectra subdirectory 296 for thatmatter (i.e., starting with step 266 of the subroutine 253 and includingeverything thereafter).

The spectra of the current plasma process which is compared with theabnormal spectra subdirectory 292 in the manner discussed in relation tothe plasma health subroutine 253 of FIG. 21 would be the spectrafollowing (in time) the spectra of the last current time t_(c) whichmatched any of the plasma processes stored in the normal spectrasubdirectory 288. Consider an example in which t₀ is 1 second and "n" is2 seconds, and further where the current plasma process "matched" withProcess A up until time t₃₉, the current plasma process "matched" withProcess B until time t₆₁, and the current plasma process "matched" withProcess C until only time t₃. The spectra from the current plasmaprocess being run in the processing chamber 36 which proceeded thelongest time into any of the plasma process stored in the normal spectrasubdirectory 288 before any deviation was identified would be thespectra at time t₆₁ from Process B. Therefore, the spectra at the timet₆₃ would be that which is compared with the abnormal spectrasubdirectory 292 in the manner described above in relation to the plasmahealth subroutine 253 of FIG. 21.

If the plasma process identified by the plasma health/processrecognition subroutine 790 was a plasma recipe stored in the normalspectra subdirectory 288, a variation of the subroutine 790 may beimplemented which may enhance the speed of the plasma health evaluation.Once the subroutine 790 identifies that the current plasma process beingrun in the chamber 36 is a plasma recipe (only one of the categories ofplasma processes which may be evaluated by the plasma health/processrecognition subroutine 790), the logic of the subroutine 790 may bemodified such that the subroutine 790 would thereafter at least startits analysis of each subsequent plasma process run in the chamber 36with that plasma recipe from the normal spectra subdirectory 288 whichwas previously identified by the subroutine 790. If the "matching"plasma process from the normal spectra subdirectory 288 happened to bethe last one which was evaluated against the current plasma process bythe subroutine 790, significant plasma health evaluation time could besaved by having it be the first plasma process from the normal spectrasubdirectory 288 which is compared with the next plasma process run inthe chamber 36. This could be particularly useful when using the plasmahealth/process recognition subroutine 790 to evaluate plasma recipes runon a cassette 6 of production wafers 18 since the same plasma recipe istypically run on each production wafer 18 from a given cassette 6. Theability of the subroutine 790 to distinguish between the same plasmarecipe run on a qualification wafer 18 versus a production wafer 18provides for further variations along this same line. Assume that thefirst wafer 18 was actually a production wafer 18 and that the plasmarecipe was identified in the first running of this plasma recipe asbeing for a production wafer 18. Each wafer 18 subsequently processedcould first be checked against the plasma recipe run for a productionwafer 18 from the normal spectra subdirectory 288, and then against theplasma recipe run for a qualification wafer 18 from the normal spectrasubdirectory 288.

Plasma Health/Process Recognition Subroutine 852--FIG. 23

The plasma health/process recognition subroutine 790 of FIG. 22 may bedescribed as incorporating a "series" logic. That is, the comparison ofthe current spectra of the plasma in the processing chamber 36 at thecurrent time t_(c) is made in relation to only one plasma process storedin the normal spectra subdirectory 288 at a time. A plasmahealth/process recognition subroutine which may be used by the processhealth module 252 and which proceeds with a "parallel" logic ispresented in FIG. 23. The plasma health/process recognition subroutine852 of FIG. 23 begins at step 854 where the Target Directory for thepattern recognition module 370 of FIG. 13 is set to the normal spectrasubdirectory 288 (i.e., the search for "matching" spectra will initiatein the normal spectra subdirectory 288). Another preliminary step of theplasma health/process recognition subroutine 852 is at step 856 where alogic operator Flag₂ is set to "T" for each of the plasma processesstored in the normal spectra subdirectory 288 to be evaluated throughthe subroutine 852. The order in which steps 854 and 856 are executed isnot particularly important in relation to the present invention.

Data relating to the current plasma process being run on product in theprocessing chamber 36 is obtained for the plasma health/processrecognition subroutine 852 at step 860. Included in this data is atleast a spectra of the plasma within the processing chamber 36 duringthe execution of a plasma process within the processing chamber 36 atthe current time t_(c), which was obtained from the chamber 36 over thePreferred Optical Bandwidth and at the Preferred Data Resolution.Basically, a comparison is thereafter made of the pattern of thiscurrent spectra at the current time t_(c) with the relevant spectra ofeach plasma process stored in the normal spectra subdirectory 288 whichhas matched the current plasma process being run in the processingchamber 36 up until the now current time t_(c), and this comparison ismade before spectra associated with a later current time t_(c) iscompared with these plasma processes stored in the normal spectrasubdirectory 288. Stated another way, the current plasma process iseffectively concurrently compared with each plasma process stored in thenormal spectra subdirectory 288 which has "matched" the current plasmaprocess being run in the processing chamber 474 up until the currentpoint in time. If the current spectra at a current time t_(c) does notmatch a particular plasma process stored in the normal spectrasubdirectory 288, this plasma process is dropped from the list ofpossible plasma processes and spectra at new, later in time, currenttimes t_(c) are no longer compared with this plasma process. "Relevance"in terms of which spectra of a given plasma process stored in the normalspectra subdirectory 288 is compared with the spectra of the plasma inthe chamber 36 at the current time t_(c) by the subroutine 852 may bedetermined in accordance with either the time dependency requirement orthe progression dependency requirement discussed above in relation tothe plasma health subroutine 253 of FIG. 21. Moreover, as in the case ofthe plasma health subroutine 253 discussed above in relation to FIG. 21,the plasma health/process recognition subroutine 852 of FIG. 23 may beconfigured to make all plasma processes stored in the normal spectrasubdirectory 292 available for comparison with the current plasmaprocess, or the subroutine 852 may be configured such that only thosecertain plasma processes are made available to the plasma health/processrecognition subroutine 852.

The spectra at the current time t_(c) from step 860 of the plasmahealth/process recognition subroutine 852 is effectively concurrentlycompared with each of the relevant plasma process stored in the normalspectra subdirectory 288 the first time through the main body of theplasma health/process recognition subroutine 852. The logic operator"Flag₂ " associated with each such plasma process has been set to "T" atthe previous step 856, so the subroutine 852 will proceed through steps864 (Process A), 880 (Process B), and 892 (Process "X") to steps 868(Process A), 884 (Process B), and 892 (Process "X") to where thesubroutine 852 is directed to proceed to the pattern recognition module370 of FIG. 13. The pattern recognition module 370 determines if thepattern of the current spectra at the current time t_(c) is a "match"with the relevant spectra of the subject plasma process stored in thenormal spectra subdirectory 288 (Process A in the case of step 868,Process B in the case of step 884, and Process "X" in the case of step896). If the current spectra at the current time t_(c) "matches" therelevant spectra of the subject plasma process, the subroutine 852proceeds to step 872 where the "clock" of the subroutine 852 is adjustedby increasing the current time t_(c) by a factor of "n". The magnitudeof "n" defines the Analytical Time Resolution. The subroutine 852 thenproceeds from step 872 to step 916 where all of the plasma processesfrom the normal spectra subdirectory 288 which are still a potential"match" for the current plasma process being run in the processingchamber 36 are displayed to the appropriate personnel (e.g., on display132 in FIG. 6). Another spectra at this new current time t_(c) is thenobtained for the plasma health/process recognition subroutine 852 backat step 860 and the foregoing is repeated so long as the evaluation ofthe entirety of the current plasma process has not yet been completed bythe plasma health/process recognition subroutine 852 as noted in itsstep 918. When the current plasma process is terminated and all spectraldata has been evaluated by the plasma health/process recognitionsubroutine 852, the subroutine 852 proceeds from step 918 to 920 wherecontrol of plasma monitoring operations may be returned to, forinstance, the startup module 202 of FIG. 15.

Some plasma processes stored in the normal spectra subdirectory 288being used by the subroutine 852 sooner or later will fail to "match"the current plasma process being run in the processing chamber 36. Thatis, the pattern recognition module 370 will determine that the patternof the spectra at the current time t_(c) does not match the relevantspectra of the subject plasma process stored in the normal spectrasubdirectory 288. One or more of steps 868, 884, and 896 will then exitin such a manner that the logic operator "Flag₂ " of their respectiveplasma process will be set to "F" (at step 876 for Process A, at step888 for Process B, at step 900 for Process "X"). Any plasma process inthe normal spectra subdirectory 288 having its logic operator "Flag₂ "set to "F" will no longer be compared to the current plasma processbeing run in the processing chamber 36 by the pattern recognition module370 through the subroutine 852. Step 868 associated with Process A willbe bypassed through step 864 when the logic operator "Flag₂ " forProcess A is set to "F", step 884 associated with Process B will bebypassed through step 880 when the logic operator "Flag₂ " for Process Bis set to "F", and step 896 associated with Process "X" will be bypassedthrough step 892 when the logic operator "Flag₂ " for Recipe "X" is setto "F".

As long as at least one plasma process stored in the normal spectrasubdirectory 288 has "matched" each spectra at each new incremental timet_(c) from step 860, the plasma health/process recognition subroutine852 will continue via steps 904 and 912. However, if this is not thecase, the plasma health/process recognition subroutine 852 will exitfrom step 904 to step 908. The protocol of step 908 is directed todetermining if the current plasma process being run in the processingchamber 36 has encountered a known error/aberration that is stored inthe abnormal spectra subdirectory 292. Therefore, the plasmahealth/process recognition subroutine 852 may include the portion of theplasma health subroutine 253 of FIG. 21 which pertains to the abnormalspectra subdirectory 292 and the unknown spectra subdirectory 296 forthat matter (i.e., starting with step 266 of the subroutine 253 andincluding everything thereafter, but not shown). The spectra comparedwith the abnormal spectra subdirectory 292 in step 266 of the plasmahealth subroutine 253 would be the spectra associated with the lastcurrent time t_(c) from step 860 of the plasma health/processrecognition subroutine 852.

Now consider an example where there are three plasma processes recordedin the normal spectra subdirectory 288 (e.g, Process "X" is Process C),where "n" from step 872 is one second, where step 860 was first executedfor time t₁, where a time dependency requirement is being used by thesubroutine 852 to define what is the relevant spectra from a givenplasma process stored in the normal spectra subdirectory 288, and wherethe current plasma process being run in the processing chamber 36 hasmatched each of Processes A, B, and C through the current time t₁₀(i.e., steps 868 (Process A), 884 (Process B), and 896 (Process C) haveeach been executed 10 times). The "clock" of the subroutine 852 is thenadjusted at step 872 to t₁₁, the spectra of the plasma in the processingchamber 36 at this new time t₁₁ is obtained for the subroutine 852 atstep 860, and the subroutine 852 proceeds to steps 868, 884, and 896since the logic operator "Flag₂ " associated with each plasma processstored in the normal spectra subdirectory 288 is still "T" (steps 864,880, and 892 each exit as a "yes" condition). Assume that the currentplasma process still matches Processes A and B from the normal spectrasubdirectory 288 at the now current time t₁₁, but no longer matchesProcess C of the subdirectory 288 at the now current time t₁₁. In thiscase, step 868 for Process A and step 884 for Process B would each stillexit "yes" and proceed to step 872 where the clock of the subroutine 852would be adjusted to t₁₂. The logic operator "Flag₂ " for Processes Aand B would also still be "T", while step 896 for Process C would exitto step 900 where the logic operator "Flag₂ " for Process C would be setto "F". As such, step 916 would indicate that the current plasma processwas now only potentially Processes A and B.

The spectra for the new time t₁₂ is obtained for the subroutine 852 atstep 860 in the subject example, and the subroutine 852 proceeds to thelogic operator check for each of the plasma processes stored in thenormal spectra subdirectory 288. The subroutine 852 would continue thecomparison of the current plasma process being run in the processingchamber 36 with Processes A and B in the subject example, through steps864 and 868 for Process A and through steps 880 and 884 for Process B.However, Process C would no longer be compared with the current plasmaprocess at the current time t₁₂ since step 892 associated with Process Cwould bypass its associated comparison step 896, and would insteadproceed to step 904. The subroutine 852 would proceed with thecomparison of the current plasma process being run in the processingchamber 36 with the normal spectra subdirectory 288 since the logicoperator "Flag₂ " for each of Process A and B at step 904 was still "T"at the now current time t₁₂ based upon the logic from step 904.

Now consider that the spectra at the current time t₁₂ matches thespectra at this same time t₁₂ for Process A (via step 868), but not forProcess B (via step 884). The logic operator "Flag₂ " for Process Bwould then be set to "F" at step 888. Moreover, the "clock" of thesubroutine 852 would be adjusted to t₁₃ at step 872, and step 916 wouldindicate that Process A from the normal spectra subdirectory 288 was theonly remaining possibility for the current plasma process being runwithin the processing chamber 36. The spectra for the new current timet₁₃ is obtained for the subroutine 852 at step 860 in the subjectexample, and the subroutine 852 proceeds to the logic operator check foreach of the plasma processes stored in the normal spectra subdirectory288 which are available to the subroutine 852. The subroutine 852 wouldcontinue the comparison of the current plasma process being run in theprocessing chamber 36 only with Process A through its associated steps864 and 868. Plasma Processes B and C would no longer be compared withthe current plasma process since step 880 associated with Process Bwould bypass its comparison step 884 and direct the subroutine 852 toinstead proceed to step 904, and since step 892 associated with ProcessC would bypass its comparison step 896 and direct the subroutine 852 toproceed to step 904. The subroutine 852 would proceed with thecomparison of the current plasma process being run in the processingchamber 36 with the normal spectra subdirectory 288 via step 904 sincethe logic operator "Flag₂ " for Process A is still "T" at the nowcurrent time t₁₃.

Completion of an entire plasma process which was run in the processingchamber 36 while matching at least one plasma process stored in thenormal spectra subdirectory 288 (Process A in the above-noted example)will cause the subroutine 852 to exit from step 918 and proceed to step920. Control of the plasma monitoring operations may then be returned bystep 920 of the plasma health/process recognition subroutine 852 to, forinstance, the startup module 202 of FIGS. 13.

Plasma Health/Process Recognition Subroutine 924--FIG. 24

Yet another embodiment of a plasma health subroutine which may be usedby the plasma health module 252 is illustrated in FIG. 24. The plasmahealth/process recognition subroutine 924 is generally directed toachieving an increase in the speed of the comparison between the currentplasma process being run in the processing chamber 36 and the normalspectra subdirectory 288 by at least initially limiting the searchwithin the subdirectory 288 to a single plasma process of thesubdirectory 288. In this regard, personnel are allowed to indicatewhich plasma process is to be run in the processing chamber 36. Forinstance, the data entry device 60 for the main control unit 58 (FIG. 1)may be used to select a plasma recipe to be run from a list of plasmarecipes on the display 130. The startup module 202 could promptpersonnel to input the recipe if desired through execution of step 230of the startup routine 203 of FIG. 16. More typically, the recipe to berun on a certain lot of wafers 18 will be input somewhere in thefabrication facility (e.g., main control panel), and when the chamber 36"reads" the lot from this wafer 18, the plasma recipe which was input inassociation with this lot will be automatically run.

Once the selection has been made at step 928, the plasma health/processrecognition subroutine 924 proceeds to step 932 to confirm that thisplasma process is in fact stored in the normal spectra subdirectory 288.Information in the process genus field 322h (e.g., plasma recipe, plasmaclean, conditioning wafer) and/or process species type field 322c (e.g.,a specific plasma recipe) of FIG. 12A may be used by step 932 of theplasma health/process recognition subroutine 924 of FIG. 24.

A spectra of the plasma in the processing chamber 36 at the current timet_(c) is obtained for the subroutine 924 at step 940 if the processselected or input at step 928 was located in the normal spectrasubdirectory 288 through execution of step 936. This current spectra iscompared with the relevant spectra of the selected plasma process in thenormal spectra subdirectory 288. The comparison at step 944 of therecipe recognition subroutine 924 determines if the pattern of thecurrent spectra at the current time t_(c) (from the current plasmaprocess being run in the processing chamber 36) is a "match" with therelevant spectra of the selected plasma process stored in the normalspectra subdirectory 288. "Matches" in accordance with step 944 may beevaluated through the pattern recognition module 370 of FIG. 15."Relevance" in terms of which spectra of the selected plasma process inthe normal subdirectory 288 is compared with the spectra of the plasmain the chamber 36 at the current time t_(c) by the pattern recognitionmodule 370 may be determined in accordance with either the timedependency requirement or the progression dependency requirementdiscussed above in relation to the plasma health subroutine 253 of FIG.21.

A number of actions are undertaken if there is a "match" at step 944 ofthe plasma health/process recognition subroutine 924, and the order ofexecution of these steps is relatively insignificant in relation to thepresent invention. Initially, the "clock" of the plasma health/processrecognition subroutine 924 is adjusted by a factor of "n" (which definesthe Analytical Time Resolution) at step 948 to provide a new currenttime t_(c). Moreover, the identification of the plasma process of thecurrent operation is displayed to appropriate personnel throughexecution of step 964 (e.g., on the display 130 of FIG. 6). Finally,step 958 inquires as to whether all of the data of the current plasmaprocess has been evaluated.

Steps 940, 944, 948, 964, and 958 of the plasma health/processrecognition subroutine 924 are repeated so long as the current plasmaprocess being run on product within the processing chamber 36 is a"match" with the selected plasma process from step 928 and until all ofthe data on the current plasma process has been evaluated by thesubroutine 924, in which case control of plasma monitoring operations istransferred to, for instance, the startup module 202 of FIG. 15 throughexecution of step 962 of the subroutine 924. Any failure of the currentplasma process to "match" the process from step 928 will cause theplasma health/process recognition subroutine 924 to proceed from step944 to an options module 952. It should be noted that the options module952 may also be accessed if the plasma process selected in step 928 isnot initially located in the normal spectra subdirectory 299. How theplasma health/process recognition subroutine 924 proceeds in these typeof circumstances will likely be determined by the operator of thefacility which implements the wafer production system 2. Access to theentirety of the normal spectra subdirectory 288 for comparison againstthe current plasma process may be implemented by step 960 includingprotocol to call the plasma health subroutine 253 of FIG. 21, the plasmahealth/process recognition subroutine 790 of FIG. 22, or the plasmahealth/process recognition subroutine 852 of FIG. 23. Notification ofthe deviation of the current plasma process from the process selected instep 928 of the plasma health/process recognition subroutine 924 may beprovided through execution of step 956 which calls the process alertmodule 428 discussed above in relation to FIG. 14 and which may alsooffer one or more protocols in relation to this condition if the processcontrol feature is enabled at step 436 of the process subroutine 432.Other options such as allowing the present plasma process to beterminated (even though it may be a valid plasma process) may also beprovided (not shown).

A variation of the subroutine 924 relates to the fact that the sameplasma recipe is typically run on an entire cassette 6, and that thecassette 6 may have one or more qualification wafers 18 in with theproduction wafers 18. Even though the same plasma recipe is run on thesewafers 18, certain differences between the production wafers 18 and thequalification wafer(s) 18 may produce differences in their respectivespectral patterns. The logic of the subroutine 924 may be to firstcompare the current plasma process against the same plasma recipeassociated with a production wafer 18 in the normal spectra subdirectory288, and to compare the current plasma recipe against the same plasmarecipe associated with a qualification wafer 18 in the normal spectrasubdirectory 288 only if the current plasma recipe does not "look" likea plasma recipe for a production wafer 18. Moreover, entries for bothproduction and qualification wafers of this same plasma recipe could besimultaneously evaluated in the manner presented above in relation tothe plasma health/process recognition subroutine 852 of FIG. 23 when theplasma recipe is input to the subroutine 924.

Plasma Health/Process Step Recognition Subroutine 972--FIG. 25

Another embodiment of a subroutine which may be used by the plasmahealth module 252 is presented in FIG. 25. Not only does the subroutine972 of FIG. 25 monitor or evaluate the health of the plasma from aplasma process being run in the processing chamber 36, but thesubroutine 972 is also able to identify the current plasma step of thecurrent plasma process being run in the processing chamber 36. As such,the subroutine 972 is characterized as a plasma health/process steprecognition subroutine 972. Two factors are key to providing this plasmastep identification function. One is that the steps of the subjectplasma process actually differ sufficiently in relation to their subjectspectra such that they can be distinguished as is the case of themulti-step recipe illustrated in FIGS. 17A-C above. Another is that theidentify of the plasma step be associated in some manner with itscorresponding spectra, such as through inputting information to theplasma step field 322e discussed above in relation to FIG. 12A.

The plasma health/process step recognition subroutine 972 proceeds witha "parallel" logic and in the same manner as the plasma health/processrecognition subroutine 852 of FIG. 23. The plasma health/process steprecognition subroutine 972 of FIG. 25 begins at step 976 where theTarget Directory for the pattern recognition module 370 of FIG. 13 isset to the normal spectra subdirectory 288 (i.e., the search for"matching" spectra will initiate in the normal spectra subdirectory288). Another preliminary step of the plasma health/process steprecognition subroutine 972 is at step 980 where a logic operator Flag₃is set to "T" for each of the plasma processes stored in the normalspectra subdirectory 288. The order in which steps 976 and 980 areexecuted is not particularly important to the present invention.

Data relating to the current plasma process being run in the processingchamber 36 is obtained for the subroutine 972 at step 984. Included inthis data is a spectra of the plasma within the processing chamber 36during execution of a plasma process being run within the processingchamber 36 at the current time t_(c). Basically, a comparison isthereafter made of the pattern of this current spectra at the currenttime t_(c) with the pattern of the relevant spectra of each plasmaprocess stored in the normal spectra subdirectory 288 which has matchedthe current plasma process up until the now current time t_(c) and whichhas been made available to the subroutine 972. This comparison is madebefore the pattern of spectra associated with a later in time currenttime t_(c) is compared with these same processes stored in the normalspectra subdirectory 288. Stated another way, the current plasma processis effectively concurrently compared with each plasma process stored inthe normal spectra subdirectory 288 which has "matched" the currentplasma process up until the current point in time and which is madeavailable to the subroutine 972. If at any time the spectra at thecurrent time t_(c) from the current plasma process does not match aparticular process in the normal spectra subdirectory 288, this plasmaprocess is dropped from the list of possible plasma processes andspectra at new, later in time, current times t_(c) are no longercompared with this particular plasma process. "Relevance" in terms ofwhich spectra of the selected plasma process is compared with thespectra of the plasma in the chamber 36 at the current time t_(c) by thesubroutine 972 may be determined in accordance with either the timedependency requirement or the progression dependency requirementdiscussed above in relation to the plasma health subroutine 253 of FIG.21. Moreover, as in the case of the plasma health subroutine 253discussed above in relation to FIG. 21, the plasma health/process steprecognition subroutine 972 of FIG. 25 may be configured to make allplasma processes stored in the normal spectra subdirectory 292 availablefor comparison with the current plasma process, or the subroutine 972may be configured such that only those certain of these plasma processesare made available to the subroutine 972 in any of the above-describedmanners.

The spectra at the current time t_(c) from step 984 of the plasmahealth/process step recognition subroutine 972 is effectivelyconcurrently compared with each plasma process stored in the normalspectra subdirectory 288 the first time through the main body of thesubroutine 972. The logic operator "Flag₃ " associated with each plasmaprocess has been set to "T" at the previous step 980, so the subroutine972 will proceed through steps 988 (Process A), 996 (Process B), and1004 (Process "X") to steps 992 (Process A), 1000 (Process B), and 1008(Process "X") to where the subroutine 972 is directed to proceed to thepattern recognition module 370 of FIG. 13. The pattern recognitionmodule 370 determines if the pattern of the current spectra at thecurrent time t_(c) is a "match" with the pattern of the relevant spectraof the subject plasma process stored in the normal spectra subdirectory288 (Process A in the case of step 992, Process B in the case of step1000, and Process "X" in the case of step 1008). If the pattern of thecurrent spectra at the current time t_(c) "matches" the pattern of therelevant spectra of the subject plasma process from the subdirectory288, the subroutine 972 proceeds to step 1012 where the clock of thesubroutine 972 is adjusted by increasing the current time t_(c) by afactor of "n". The magnitude of "n" defines the Analytical TimeResolution (i.e., what portion of the collected data is actuallyanalyzed). The subroutine 972 then proceeds from step 1012 to step 1016where all of the plasma processes from the normal spectra subdirectory288 which are still a potential "match" for the current plasma processbeing run in the processing chamber 36 are displayed to the appropriatepersonnel (e.g., on display 130 in FIG. 6). Moreover, the specificprocess step, if any, of each of these potential plasma processes isalso displayed at step 1016. Another spectra at the new current timet_(c) is then obtained back at step 984 and the foregoing is repeated solong as the evaluation of the entirety of the current plasma process hasnot yet been completed by the plasma health/process step recognitionsubroutine 972 as noted in step 1044. When the plasma process isterminated and all spectral data has been evaluated by the plasmahealth/process step recognition subroutine 972, the subroutine 972 willproceed from step 1044 to 1048 where control of plasma monitoringoperations may be returned to, for instance, the startup module 202 ofFIG. 15.

Some plasma processes in the normal spectra subdirectory 288 sooner orlater will fail to "match" the current plasma process being run in theprocessing chamber 36. That is, the pattern recognition module 370 willdetermine that the pattern of the spectra at the current time t_(c) doesnot match the pattern of the relevant spectra of the subject plasmaprocess stored in the normal spectra subdirectory 288. One or more ofsteps 992, 1000, and 1008 will then exit in such a manner that the logicoperator "Flag₃ " of their respective plasma process will be set to "F"(at step 1020 for Process A, at step 1024 for Process B, at step 1028for Process "X"). Any plasma process stored in the normal spectrasubdirectory 288 in which its logic operator "Flag₃ " is set to "F" willno longer be compared to the current plasma process by the patternrecognition module 370. Step 992 associated with Process A will bebypassed through step 988 when the logic operator "Flag₃ " for Process Ais set to "F", step 1000 associated with Process B will be bypassedthrough step 996 when the logic operator "Flag₃ " for Process B is setto "F", and step 1008 associated with Process "X" will be bypassedthrough step 1004 when the logic operator "Flag₃ " for Process "X" isset to "F".

As long as at least one plasma process from the normal spectrasubdirectory 288 has "matched" each spectra at each new incremental timet_(c) from step 984, the plasma health/process step recognitionsubroutine 972 will continue via steps 1032 and 1036. However, if thisis not the case, the subroutine 972 will proceed from step 1032 to step1040. The protocol of step 1040 is directed to determining if thecurrent plasma process being run in the processing chamber 36 hasencountered a known error/aberration that is stored in the abnormalspectra subdirectory 292. Therefore, the plasma health/processrecognition subroutine 972 may include the portion of the plasma healthsubroutine 253 of FIG. 21 which pertains to the abnormal spectrasubdirectory 292 and the unknown spectra subdirectory 296 (i.e.,starting with step 266 of the subroutine 253 and including everythingthereafter). The spectra compared with the abnormal spectra subdirectory292 would then be the spectra associated with the last current timet_(c) from step 984 of the plasma health/process step recognitionsubroutine 972.

Exemplary "Aging Chamber" Spectra--FIGS. 26A-C

The primary purpose of the plasma health module 252 is to monitor thehealth of the plasma used to execute a plasma process within the chamber36. As noted above, the running of plasma processes on product in thechamber 36 will eventually start to adversely impact its performance.This "aging" chamber condition is often, if not always, reflected by thespectra of the plasma in the chamber 36 during a plasma process. How thepattern of the spectra of the plasma may change over time as the chamber36 "ages" is illustrated in FIGS. 26A-C.

FIG. 26A presents a spectra 1052 of an exemplary plasma when theprocessing chamber 36 is in a clean condition and while running acorresponding plasma recipe on product (e.g., a "healthy" plasma). FIG.26B presents a spectra 1060 of this same exemplary plasma after a numberof plasma recipes have been conducted within the processing chamber 36and while this same plasma recipe is actually being run on product inthe chamber 36. Although the plasma recipes run in the chamber 36between the times associated with FIG. 26A and 26B have started to agethe chamber 36, the interior of the chamber 36 has not sufficientlydegraded the health of plasma to the point where the chamber 36 needs tobe cleaned. Finally, FIG. 26C presents a spectra 1068 of this sameexemplary plasma, during the running of the same plasma recipe onproduct in the same chamber 36 as presented in FIGS. 26A-B, and wherethe running of the previous plasma recipes on product in the processingchamber 36 has further deteriorated the condition of the interior of theprocessing chamber 36. This spectra 1068 may be selected by the operatorof the facility implementing the wafer production system 2 as beingindicative of the chamber 36 being in condition for cleaning (e.g.,"dirty/unhealthy plasma", a "dirty chamber" condition). For instance, ifthe product processed in the chamber 36 was defective in some manner,and if analysis of the product traced the cause back to the condition ofthe chamber 36, spectral data from the run associated with thisdefective product may be selected as being indicative of the subjectcondition. However, it should be appreciated that it may be desirable tohave a dirty chamber condition identified before it starts ruiningproduct processed in the chamber 36. That is, it may be desirable toidentify a trend which is that the condition of the chamber 36 isdegrading and associate this trend with a dirty chamber condition suchthat product is not lost because of a dirty chamber condition. This maybe implemented by associating spectral data from runs previous to thatwhere the defective product was produced with a dirty chamber condition(even though the product produced thereby was not yet defective). Eachof the spectra 1052, 1060, and 1068 are characterized by a number ofpeaks 1056, 1064, and 1072, respectively, of varying intensities(plotted along the "y" axis and expressed in "counts" which isreflective of the intensity level) at various wavelengths (plotted alongthe "x" axis in nanometers). A comparison of the spectra 1052, 1060, and1068 reveals that their associated patterns are in fact different,including without limitation as follows: 1) at about the 440 nanometerwavelength region, peak 1056a in the spectra 1052 of FIG. 26A has anintensity of about 3,300, peak 1064a in the spectra 1060 of FIG. 26B hasan intensity of about 3,300, and peak 1072a in the spectra 1068 of FIG.26C has an intensity of about 2,700; 2) at about the 525 nanometerwavelength region, peak 1056b in the spectra 1052 of FIG. 26A has anintensity of about 2,800, peak 1064b in the spectra 1060 of FIG. 26B hasan intensity of about 2,900, and peak 1072b in the spectra 1068 of FIG.26C has an intensity of about 2,100; 3) at about the 560 nanometerwavelength region, peak 1056d in the spectra 1052 of FIG. 26A has anintensity of about 400, peak 1064d in the spectra 1060 of FIG. 26B hasintensity of about 700, and peak 1072d in the spectra 1068 of FIG. 26Chas an intensity of about 1,200; 4) at about the 595 nanometerwavelength region, peak 1056e in the spectra 1052 of FIG. 26A has anintensity of about 2,100, peak 1064e in the spectra 1060 of FIG. 26B hasintensity of about 2,000, and peak 1072e in the spectra 1068 of FIG. 26Chas an intensity of about 2,000; and 5) at about the 625 nanometerwavelength region, there is substantially no peak in the spectra 1052 ofFIG. 26A, although this region has an intensity of about 200 (noise),peak 1064f in the spectra 1060 of FIG. 26B has intensity of about 900,and peak 1072f in the spectra 1068 of FIG. 26C has an intensity of about1,500. These are but a few examples, as it should be clear that thepeaks 1056 of spectra 1052 of FIG. 26A, the peaks 1064 of the spectra1060 of FIG. 26B, and the peaks 1072 of the spectra 1068 of FIG. 26Cdiffer as to one or more of their respective wavelengths and intensitiesin a manner which would allow these types of spectra to be used as abasis to determine when to clean the chamber 36. That is, thedistinctiveness of the patterns between the spectra 1052, 1060, and 1068may be utilized to apprise the appropriate personnel of the condition ofthe processing chamber 36 in relation to cleaning schedules.

At least two options exist for implementing the spectra in the plasmaspectra directory 284 of FIG. 9 which are at least deemed indicative ofa chamber 36 which is in need of cleaning. Spectra of plasma in a dirtychamber condition may be included in the abnormal spectra subdirectory292 of FIG. 9. In this case, the plasma health subroutine 253 of FIG.21, the plasma health/process recognition subroutine 790 of FIG. 22, theplasma health/process recognition subroutine 852 of FIG. 23, the plasmahealth/process recognition subroutine 924 of FIG. 24, and the plasmahealth/process step recognition subroutine 972 of FIG. 25 would eachthen include "chamber condition monitoring" capabilities in the mannerpresented above. How one or more spectra which is indicative of a dirtychamber condition may be obtained is as follows. Consider the situationwhere a plasma recipe being run on product in the processing chamber 36does not "match" any plasma recipe stored in the normal spectrasubdirectory 288, and further does not "match" any of the knownerrors/aberrations stored in the abnormal spectra subdirectory 292 suchas discussed above in relation the plasma health subroutine 253 of FIG.21. The spectra of the plasma from this plasma recipe would then bestored in the unknown spectra subdirectory 296. When spectra from thisplasma recipe are subsequently examined and determined to be associatedwith a dirty chamber condition, at least one of the spectra from thisplasma recipe which did not "match" any entry in the normal spectrasubdirectory 288 or the abnormal spectra subdirectory 292 may beselected as being indicative of the dirty chamber condition. Thisspectra may then be transferred to the abnormal spectra subdirectory 292such that this spectra will be identified as a known error condition.The protocol which may be implemented (either automatically or manually)upon encountering this same condition in subsequent executions of plasmaprocesses in this same chamber 36 may be as set forth above in thediscussion of the process alert subroutine 432 of FIG. 14. One or morealerts of the dirty chamber condition may also be issued consistent withthe above discussion.

Chamber Condition Module 1084--FIGS. 27-29

Another way of implementing spectra indicative of a dirty chambercondition is to include this data in a chamber condition subdirectory300 and to utilize a chamber condition module 1084 which is separatefrom the plasma health module 252. One embodiment of a subroutine whichmay be used to monitor the condition of the chamber 36 through acomparative analysis with the chamber condition subdirectory 300 isillustrated in FIG. 27. There are a number of ways in which the chambercondition subroutine 406 of FIG. 27 may be implemented to monitorcurrent plasma processes being run in the chamber 36. The loop 190 ofthe plasma health subroutine 253 of FIG. 16 may include protocol in itsstep 194 to call the chamber condition subroutine 406 of FIG. 27. Thatis, the subroutine 406 may be called by the plasma health subroutine 253for each execution of step 254 of the subroutine 253 where a currentspectra at the current time t_(c) is obtained for the subroutine 253.This same spectra may then be made available to the chamber conditionsubroutine 406 through execution of step 410 of the subroutine 406. Thepattern of this spectra may then compared with the pattern of spectra inthe chamber condition subdirectory 300 at step 412 (step 408 of thesubroutine 406 sets the Target Directory for the pattern recognitionmodule 370 of FIG. 13 to the chamber condition subdirectory 300). Morespecifically, step 412 of the chamber condition subroutine 406 directsthe subroutine 406 to go to the pattern recognition module 370 of FIG.13. If the pattern of the spectra of the plasma in the processingchamber 36 at the then current time t_(c) does not "match" the patternof any spectra in the chamber condition subdirectory 300, the chambercondition subroutine 406 will proceed from step 414 to step 416. Controlis then returned to the loop 190 of the plasma health subroutine 253 ofFIG. 21 where the "clock" is adjusted by an increment of "n" at its step278. Another spectra is then obtained for the chamber conditionsubroutine 406 at this new current time t_(c) when step 194 of the loop190 from the plasma health subroutine 253 of FIG. 21 is againencountered, which calls the chamber condition subroutine 406 of FIG. 27for a repetition of the above-described analysis. Any of the subroutines790, 852, 924, and 972 for providing plasma health evaluations mayinclude this type of feature (not shown).

The chamber condition subroutine 406 of FIG. 27 will continue to executein the above-noted manner until one of two conditions is met. The firstis when plasma monitoring operations are terminated through the plasmahealth subroutine 253 of FIG. 21, such as when all of the data on thecurrent plasma process has been evaluated and the plasma processingoperations have been terminated. The second condition which will causethe termination of the chamber condition subroutine 406 in theabove-described manner is when the pattern recognition module 370indicates that there is a match between the spectra of the plasma in theprocessing chamber 36 at the then current time t_(c) and at least onespectra in the chamber condition subdirectory 300. In this case thesubroutine 406 will proceed from step 414 to step 418 where the chambercondition subroutine 406 of FIG. 44 transfers control to the processalert module 428 where any of the actions described above in relation toa dirty chamber condition may be initiated.

The chamber condition subroutine 406 may be run in parallel with theplasma health module 252 each time the plasma health module 252 isaccessed (e.g., by having step 236 of the startup routine 203 alsoinclude protocol to call the chamber condition subroutine 406). In thiscase, an additional step of adjusting the clock would have to beincluded, as well as a loop defined by this step as well as steps 410,412, and 414 in a manner similar to the other subroutines presentedherein.

There are ways of determining when the interior of the processingchamber 36 is in condition for cleaning other than comparing a patternof a current spectra of the plasma in the chamber 36 against the patternof a spectra which has been previously associated with a dirty chambercondition. One such way is implemented by the chamber conditionsubroutine 1088 presented in FIG. 28. The premise employed by thechamber condition subroutine 1088 is that the interior of the processingchamber 36 has degraded to the point where a cleaning operation shouldbe employed when the time required to complete any plasma step of amultiple step plasma process takes longer than a time limit previouslyestablished for the plasma step. The time required to complete a plasmastep may increase as the condition of the interior of the processingchamber 36 degrades. As an example, a given plasma step may take 30seconds to achieve its desired/predetermined end result in a "clean"processing chamber 36, may take 50 seconds in a chamber 36 which is atan intermediate time in relation to a "cleaning" cycle, and may take inexcess of 70 seconds under dirty chamber conditions. In some cases theprocessing chamber 36 may actually degrade to the point where the resultof the plasma step may never be realized. Therefore, the chambercondition subroutine 1088 assumes that when a given plasma step takeslonger than its associated time limit, the associated cause is theexistence of a dirty chamber condition.

Since the chamber condition subroutine 1088 needs to "know" the identifyof both the plasma process and the process step to execute its analysis,the chamber condition subroutine 1088 may be integrated in some mannerwith the operation of any one or more of the plasma health/processrecognition subroutine 790 of FIG. 22, the plasma health/processrecognition subroutine 852 of FIG. 23, or the plasma health/processrecognition subroutine 924 of FIG. 24 (e.g., by being incorporatedtherein, by being called simultaneously therewith). In each of thesecases, once the identity of the plasma process is determined, one willknow each of the particular plasma steps which are included in thisplasma process. In addition, the chamber condition subroutine 1088 mayalso be integrated in some manner with the plasma health/process steprecognition subroutine 972 of FIG. 25 which identifies the currentplasma step being executed in the chamber 36.

Referring to FIG. 28, a maximum time limit for each plasma step, if any,of the plasma process to be run in the chamber 36 should be obtained bythe chamber condition subroutine 1088 at its step 1092. Personnel maymanually input the maximum time limit for the subject plasma step(s) ofthe plasma process with the data entry device 132 for purposes of step1092 of the chamber condition subroutine 1088. A more preferred approachis to include these time limits in the maximum total process step timefield 322f for the main data entry 350 of the plasma process as storedin the normal spectra subdirectory 288 (FIG. 12A). The maximum timelimit may be empirically determined and input to the subject maximumtotal process step time field 322f. Alternatively, the limits referredto in step 1092 may simply coincide with a time in which the operator ofthe fabrication facility employing the wafer production system 2 hasdetermined is necessary to maintain a desired production rate, whichwould then be input to the subject maximum total process step time field322f. Information for step 1092 of the chamber condition subroutine 1088may then be automatically retrieved from the corresponding maximum totalprocess step time field 322f of FIG. 12A which is associated with thecurrent plasma process step being run in the chamber 36.

The amount of time required to complete each plasma step of the currentplasma process being run in the processing chamber 36 is monitored atstep 1096 of the chamber condition subroutine 1088. A process step clock(not shown) is started once the subject plasma step is initiated andwill not stop until the termination of this plasma step. Step 1096 mayutilize the endpoint detection module 1200 to be discussed below inrelation to FIGS. 52-58 to identify the endpoint of the current plasmastep. A comparison is made at step 1100 of the chamber conditionsubroutine 1088 between the time spent on the current plasma step fromstep 1096 and its associated maximum time limit from step 1092. So longas this limit has not yet been exceeded, the chamber conditionsubroutine 1088 will proceed to step 1108 where a determination is madeas to whether the current plasma process has been terminated. Anycontinuation of the plasma process will allow the chamber conditionsubroutine 1088 to continue its analysis through execution of steps 1096and 1100 as described. When the plasma process is terminated, however,the subroutine 1088 will proceed from step 1108 to step 1112 wherecontrol of plasma monitoring operations may be returned to, forinstance, the startup module 202 of FIG. 15.

The chamber condition subroutine 1088 will continue to execute in theabove-noted manner unless the time spent on the current plasma processstep exceeds its corresponding maximum time limit. In this case thechamber condition subroutine 1088 will proceed from step 1100 to step1104 where the process alert module 428 of FIG. 14 is called for a dirtychamber condition, and where the above-noted types of actions may thenbe undertaken. If the process alert module 428 of FIG. 14 is configuredto return control to the module which called the module 428, the chambercondition subroutine 1088 may include a step after step 1104 to returncontrol of plasma monitoring operations to, for instance, the startupmodule 202 of FIG. 15.

Another way of determining when the interior of the processing chamber36 is in condition for cleaning is embodied by the chamber conditionsubroutine 1120 presented in FIG. 29 and which may be implemented in thesame way as the chamber condition subroutine 1088 described above inrelation to FIG. 28. The premise employed by the chamber conditionsubroutine 1120 is that the interior of the processing chamber 36 hasdegraded to the point where a cleaning operation should be employed whenthe time required to complete an entire plasma process (all of theplasma steps) takes longer than a time limit previously established forcompleting the plasma process. The time required to complete an entireplasma process may increase as the condition of the interior of theprocessing chamber 36 degrades, such as by the formation of deposits onits interior surfaces. As an example, a given plasma process may take180 seconds to achieve its desired/predetermined result in a "clean"processing chamber 36, may take 220 seconds in a chamber 36 which is atan intermediate time in relation to a "cleaning" cycle, and may take inexcess of 300 seconds when in a dirty chamber condition. In some casesthe processing chamber 36 may actually degrade to the point where thedesired end result of the plasma process may never be realized.Therefore, the chamber condition subroutine 1120 assumes that when agiven plasma process takes longer than its associated time limit, theassociated cause is the existence of a dirty chamber condition.

Since the chamber condition subroutine 1120 needs to "know" the identifyof plasma process to execute its analysis, the chamber conditionsubroutine 1120 may be integrated in some manner with the operation ofany one or more plasma health/process recognition subroutine 790 of FIG.22, the plasma health/process recognition subroutine 852 of FIG. 23, orthe plasma health/process recognition subroutine 924 of FIG. 24 (e.g.,by being incorporated therein, by being called simultaneouslytherewith). In addition, the chamber condition subroutine 1088 may alsobe integrated in some manner with the plasma health/process steprecognition subroutine 972 of FIG. 25 which also identifies the currentplasma process being executed in the chamber 36, as well as theindividual process step.

Referring to FIG. 29, a maximum time limit for the plasma process to berun in the chamber 36 is input to the chamber condition subroutine 1120at its step 1124. Personnel may manually input the maximum time limitfor the subject plasma process with the data entry device 132 forpurposes of step 1124 of the chamber condition subroutine 1120. A morepreferred approach is to include this time limit in the maximum totalprocess time field 322g for the main data entry 350 of the subjectplasma process as stored in the normal spectra subdirectory 288. Themaximum time period may be empirically determined and input to thesubject maximum total recipe time field 322g. Alternatively, the limitreferred to in step 1124 may simply coincide with a time in which theoperator of the fabrication facility employing the wafer productionsystem 2 has determined is necessary to maintain a desired productionrate, which would then be input to the subject maximum total recipe timefield 322g. Information for step 1124 may then be automaticallyretrieved from the corresponding maximum total process time field 322gof FIG. 12A which is associated with the current plasma process beingrun in the chamber 36.

The amount of time required to complete the current plasma process beingrun in the processing chamber 36 is monitored at step 1128 of thechamber condition subroutine 1120. A recipe clock (not shown) is startedonce the plasma process is initiated (e.g., when the plasma comes "on"in the chamber 36) and will not stop until the plasma process isterminated (e.g., when the plasma goes "off" in the chamber 36). Step1128 may also utilize the endpoint detection module 1200 to be discussedbelow in relation to FIGS. 52-58. A comparison is made at step 1132 ofthe chamber condition subroutine 1120 between the time spent on thecurrent plasma process from step 1128 and its associated maximum timelimit from step 1124. So long as this limit has not yet been exceeded,the chamber condition subroutine 1120 will proceed to step 1140 where adetermination is made as to whether the current plasma process has beenterminated. Any continuation of the plasma process will allow thechamber condition subroutine 1120 to continue its analysis throughexecution of steps 1128 and 1132 in the described manner. When theplasma process is terminated, however, the subroutine 1120 will proceedfrom step 1140 to step 1144 where control of plasma monitoringoperations may be returned to, for instance, the startup module 202 ofFIG. 15.

The chamber condition subroutine 1120 will continue to execute in theabove-noted manner unless the time spent on the current plasma processexceeds its corresponding maximum time limit. In this case the chambercondition subroutine 1120 will proceed from step 1132 to step 1136 wherethe process alert module 428 of FIG. 14 is called based upon a dirtychamber condition, and where the above-noted actions may be undertaken.If the process alert module 428 of FIG. 14 is configured to returncontrol to the module which called the module 428, the chamber conditionsubroutine 1120 may include a step after step 1136 to return control ofplasma monitoring operations to, for instance, the startup module 202 ofFIG. 15.

Exemplary Spectra of Cleaning Procedure--FIGS. 30A-D

Some time after a "dirty chamber condition" has been identified in anyof the above-noted manners, the chamber 36 will undergo a cleaningoperation of some type. FIGS. 30A-D illustrate the differences in thespectral patterns of the plasma in the chamber 36 at various stages toillustrate how the current plasma process module 250 not only canevaluate the health of the subject plasma process, but how it candistinguish between different types of plasma processes through spectralanalysis. FIG. 30A is an exemplary spectra of a plasma recipe beingconducted in a processing chamber 36 which has been determined to be inneed of a cleaning operation. Compare this spectra 1440 of FIG. 30A withthe spectra 1450 of FIG. 30D which is this same plasma recipe in thissame processing chamber 36, but when in a clean condition and after aconditioning wafer operation has been completed to prepare the chamber36 for processing production wafers 18. Note the different intensitiesof the peaks in these two spectras 1440 and 1450 at the variouswavelengths. There are two strong peaks around the 550 nanometerwavelength region in the spectra 1440 of FIG. 30A, compared to only onestrong peak in this wavelength region of the spectra 1450 of FIG. 30D.Also note the existence of a strong peak in the spectra 1440 of FIG. 30Aat about the 625 nanometer wavelength region, compared with no strongpeak in the spectra 1450 of FIG. 30D. These differences can be readilyidentified to in turn identify when the processing chamber 36 should becleaned in at least some manner.

The cleaning protocol illustrated in FIG. 30 starts with a wet cleanwhere the chamber 36 is vented and opened such that interior surfaces ofthe chamber 36 may be wiped with one or more appropriate solvents. Aplasma cleaning operation may have been previously run in the chamber36, but may have been unable to adequately address the condition of theinterior of the chamber 36 to the desired degree. After the wet clean,the chamber 36 is resealed and a plasma is introduced into the chamber36 with no product therein. The spectra 1444 of FIG. 30B is of anexemplary plasma within the processing chamber 36 with no producttherein at the start of such a plasma cleaning operation. Compare thisspectra 1444 from FIG. 30B with the spectra 1448 of FIG. 30C which isthis same plasma in this same processing chamber 36, but after all ofthe residuals from the wet clean have been removed by the plasma clean.Note the different intensities of the peaks in these two spectras 1444and 1448 at the various wavelengths, particularly between the 650 and750 nanometer wavelength region where the spectra 1444 FIG. 30B has twosubstantial peaks and where the intensity of these same peaks aresignificantly reduced in the spectra 1448 of FIG. 30C.

Finally, compare the spectra 1448 at the end of plasma clean and thespectra 1450 at the end of a conditioning wafer operation. The spectra1448 of FIG. 30C is of an exemplary plasma within the processing chamber36 at the end of a plasma clean of the chamber 36 which hasappropriately addressed the residuals of the wet clean. Compare thisspectra 1448 from FIG. 30C with the spectra 1450 of FIG. 30D which isthis same plasma in this same processing chamber 36, but after a numberof conditioning wafers have been processed in the chamber 36. Note thedifferent intensities of the peaks in these two spectras 1448 and 1450at the various wavelengths, particularly between the 650 and 750nanometer wavelength region where the spectra 1448 of FIG. 30C has twopeaks and where the spectra 1450 of FIG. 30D has no peaks in thisregion.

Plasma Monitoring Assembly 500--FIGS. 31-36

Degradation of the interior of the processing chamber 36 from plasmaprocesses run therein also degrades the inner surface 40 of the window38 on the chamber 36 which is exposed to the plasma (the outer surface42 being isolated from the plasma, and thereby not affected by theplasma). Recall that data for the current plasma process module 250 inthe nature of optical emissions of the plasma in the chamber 38 isobtained through the window 38. Therefore, as the window 38 degrades, soto may the reliability of the results of the current plasma processmodule 250. An embodiment which addresses this condition, as well asother conditions which may adversely impact the reliability of theresults provided by the current plasma process module 250, is presentedin FIG. 31 in the nature of the plasma monitoring assembly 500.

The plasma monitoring assembly 500 of FIG. 31 includes all of thefeatures discussed above in relation to the plasma monitoring assembly174 of FIG. 6. In this regard, the plasma monitoring assembly 500includes a plasma monitoring module 560 (FIGS. 31-32), which includesall of the same modules as identified above in relation to the plasmamonitoring module 200 of FIG. 7 and which is part of the PMCU 128'(e.g., the same current plasma process module 250 and all of itssub-modules). Moreover, the spectrometer assembly 506 and CCD array 548are also the same in relation to the similarly identified components ofthe plasma monitoring assembly 174 of FIG. 6. Increases in the accuracyof the evaluation of plasma processes by the current plasma processmodule 250 are available by obtaining the data for the module 250through the plasma monitoring assembly 500 because of its calibrationcapabilities. Specifically, the plasma monitoring assembly 500, and morespecifically its plasma monitoring module 560, includes a windowmonitoring or calibration assembly 552 which includes a windowmonitoring or calibration module 562 which is also part of the plasmamonitoring module 560 as illustrated in FIG. 32. The PMCU 128' istherefore the same as presented above in relation to the plasmamonitoring assembly 174 of FIG. 6, except that it includes thisadditional feature in relation to the calibration module 562. As such,the "prime" designation is utilized in relation to the PMCU 128 of FIG.31.

The calibration assembly 552 provides certain advantages for the plasmamonitoring assembly 500 of FIG. 31 over the plasma monitoring assembly174 of FIG. 6. The calibration assembly 552 of FIG. 31 provides two mainfunctions. One of these functions is to calibrate the current plasmaprocess module 250 (FIGS. 7 and 32) for any wavelength shift of thespectra of the plasma within the processing chamber 36. Wavelengthshifts may be attributed to the spectrometer assembly 506, but may alsoexist for other reasons. Another function provided by the calibrationassembly 552 of FIG. 31 is to calibrate the current plasma processmodule 250 for any intensity shift of the spectra of the plasma withinthe processing chamber 36. Intensity shifts may be due to an "aging" ofthe window 38 on the chamber 36 through which optical emissions areobtained, but may also be due to other conditions. Since the window 478in FIG. 31 has a different configuration than the window 38 presented inFIG. 6, a different reference numeral is used not only for the window,but for the processing chamber as well. Therefore, the processingchamber of FIG. 31 identified by the reference number 474 may be used inplace of one or more of the chambers 36 presented in FIG. 1.

The calibration assembly 552 of FIG. 31 includes a calibration lightsource 556 which is operatively interfaced with the window 478 of theprocessing chamber 474 by a fiber optic cable assembly 504. In oneembodiment this calibration light 556 source actually has a firstcalibration light source 556a and a second calibration light source556b. The first calibration light source 556a uses a first type of lightto identify wavelength shifts associated with the plasma monitoringassembly 500. Intensity shifts are identified through the secondcalibration light source 556b which uses a second type of light which isdifferent than the first type of light. Benefits associated with the useof two different types of light for identifying wavelength and intensityshifts, respectively, will be addressed in relation to the calibrationmodule 562 and FIGS. 40-48. Although not preferred, the same type oflight could be used to identify both intensity and wavelength shifts(e.g., light having a plurality of discrete intensity peaks).

The fiber optic cable assembly 504 also operatively interfaces thewindow 478 with the spectrometer assembly 506 such that the windowmonitoring assembly 552 is able to directly monitor the condition of thewindow 478. Generally, a calibration light is directed to the window 478from the calibration light source 556 through the fiber optic cableassembly 504, preferably when there is no plasma within the processingchamber 474. As such, operation of the calibration assembly 552 is notdependent in any manner on the plasma within the chamber and its data isin fact independent of any data relating to the plasma. A portion of thecalibration light is reflected by the window 478 and is directed by thefiber optic cable assembly 504 to the spectrometer assembly 506.

The spectrometer assembly 506 of FIG. 31 preferably is of thesolid-state type, and in one embodiment includes three individual solidstate spectrometers 516a-c, each of which analyzes a differentwavelength region and as illustrated in FIG. 33. In this case, thespectrometer 516a may analyze the 246 nanometer to 570 nanometer region,the spectrometer 516b may analyze the 535 nanometer to 815 nanometerregion, and the spectrometer 516c may analyze the 785 nanometer to 1014nanometer region. The overlap between these individual spectrometers 516once again facilitates alignment of the three spectral segments andreduces the potential for losing optical emissions data at thetransition zones. Each of these spectrometers 516 are interconnected ineffectively parallel relation by the fiber optic cable assembly 504which is illustrated in more detail in FIG. 34.

The fiber optic cable assembly 504 of FIG. 34 includes three innercables 508 surrounded by six outer cables 512. Light from thecalibration light source 556 is directed to the window 478 through theouter cables 512 during calibration operations to be discussed below inrelation to the calibration module 562 of FIGS. 40-48, while lightreflected by the window 478 (as well as light from within the chamber474 during the running of plasma processes within the chamber 474 forthat matter, at which time the calibration assembly 552 is not activatedor running) is directed to the spectrometer assembly 506 through theinner cables 508 of the fiber optic cable assembly 504. One inner cable508 of the fiber optic cable assembly 504 is directed to each of thespectrometers 516 of the spectrometer assembly 506 as illustrated inFIG. 33. This data received by the spectrometer assembly 506 from thecalibration light source 556 is directly from the inner surface 482 ofthe window 474, and therefore it is proper to characterize thecalibration assembly 552 as directly monitoring the condition of theinner surface of the window 478.

One function of the calibration assembly 552 is to determine the effect,if any, that the inner surface 482 of the window 478 is having on thelight being emitted from the processing chamber 474 during plasmaprocesses since this light is used by the current plasma process module250. The calibration assembly 552 also addresses the presence of theouter surface 486 of the window 478. As can be seen in FIG. 31 and inFIG. 35, the outer surface 486 and inner surface 482 of the window 478are disposed in a non-parallel relationship. Stated another way and asillustrated in both FIGS. 31 and 35, the inner surface 482 of the window478 is disposed at least substantially perpendicular to a reference axis490 which coincides with the primary axis of the light from thecalibration light source 556 as it is directed toward the window 478,whereas the outer surface 486 of the window 478 is disposed innon-perpendicular relation to this reference axis 490. In oneembodiment, the angle between the reference axis 490 and the outersurface 486 of the window 478 is within the range of about 2° to about45°, and in another embodiment this angle is less than the criticalangle. This relative positioning of the inner surface 482 and outersurface 486 of the window 478 has the effect of having that portion ofthe calibration light, which is reflected by the outer surface 486 ofthe window 478, be directed away from the axis 490 and thereby away fromthe inner cables 508 of the fiber optic cable assembly 504 which lead tothe spectrometer assembly 506. Therefore, when a calibration light issent from the calibration light source 556 to the window 478 through theouter cables 512 of the fiber optic cable assembly 504, the onlysignificant portion of light which the inner cables 508 of the fiberoptic cable assembly 504 "sees" is the light which is reflected by theinner surface 482 of the window 478--not from the outer surface 486 ofthe window 478. The inner surface 482 of the window 478 is that which isaffected by conducting plasma processes within the processing chamber474, and which thereby affects the light which is emitted from theprocessing chamber 474 through the window 478. Therefore, the lightreceived by the spectrometer assembly 506 during calibration operationsby the window monitoring assembly 552 presents a more accurate depictionof the condition of the inner surface 482 of the window 486. Furtherenhancement may be realized by incorporating a broad bandanti-reflection coating (e.g., of multiple-layer or laminatedconstruction) on the outer surface 486 of the window 478 at least inthat region where the calibration light impacts the outer surface 486.These types of coatings increase the amount of the calibration lightwhich passes through the outer surface 486 of the window 478 to theinner surface 482 by reducing the amount of the calibration light whichis reflected by the outer surface 486.

Maintaining a proper relative positioning between the fiber optic cableassembly 504 and the window 478 on the chamber 474 is important to theoperation of not only the calibration module 562, but the current plasmaprocess module 250 as well. One way of interconnecting the fiber opticcable assembly 504 and the window 478 is illustrated in FIG. 36 in thenature of a fixture assembly 1534. The fixture assembly 1534 includes awindow fixture 1538 which securely retains the window 478 and allows fordetachable interconnection of the same with the processing chamber 474(e.g, via one or more threaded fasteners). A cavity or recess 1542exists within an interior portion of the window fixture 1538 andinterfaces with the outer surface 486 of the window 478. Surfaces of thewindow fixture 1538 which define the recess 1542 are black anodized soas to absorb any portion of the calibration light from the calibrationlight source 506 which is reflected by the outer surface 486 of thewindow 478 during calibration operations. Light absorbing coatings couldalso be utilized to provide this function.

The fixture assembly 1534 also includes a fiber fixture 1546 which isappropriately interconnected (e.g., detachably) with the window fixture1538 (e.g., via one or more threaded fasteners). The recess 1542 in thewindow fixture 1538 is thereby a closed space in the assembled conditionvia the outer surface 486 of the window 478 and a portion of the backside of the fiber fixture 1546. Appropriate treatment of the portion ofthe fiber fixture 1546 which closes the recess 1542 may also beimplemented to reduce the potential for that portion of the calibrationlight which is reflected by the outer surface 486 of the window 478interfering with that portion of the calibration light which isreflected by the inner surface 482 of the window 478 and provided to thespectrometer assembly 506 via the fiber optic cable assembly 504.

The fiber optic cable assembly 504 is removably or detachablyinterconnected with the fiber fixture 1546 by a fiber fixture coupling1554 on the fiber fixture 1546 and a cable coupling 1558 on an end ofthe fiber optic cable assembly 504 which houses both the inner cables508 and the outer cables 512 (FIG. 34). The ends of the inner cables 508and outer cables 512 project toward the outer surface 486 of the window478 in axial alignment with a port 1550 which extends through the fiberfixture 1546 to intersect the recess 1542 in the window fixture 1538.Therefore, calibration light from the calibration light source 556 isdirected through the outer cables 512, through the port 1550 in thefiber fixture 1546, through the recess 1542 in the window fixture 1538,and to the outer surface 486 of the window 478. Calibration light whichis reflected by the inner surface 482 of the window 478 travels throughthe recess 1542 in the window fixture 1538, through the port 1550 in thefiber fixture 1546, into the inner cables 508 of the fiber optic cableassembly 504, and to the spectrometer assembly 506. The particularmanner in which calibration operations are undertaken using theforegoing arrangement is addressed in relation to the calibration module562 of FIGS. 40-48.

Plasma Monitoring Assembly 700--FIGS. 37-39

Another embodiment of a plasma monitoring assembly which also reducesthe potential for that portion of the calibration light which isreflected by the outer surface of the window interfering with thatportion of the calibration light which is reflected by the inner surfaceof the window and provided to the calibration module 562 (FIG. 32) isillustrated in FIG. 37. This embodiment may be used in place of theplasma monitoring assembly 500 of FIG. 31 although the configurationpresented in FIG. 31 is more preferred. The plasma monitoring assembly700 of FIG. 37 generally includes a calibration assembly 726, thecalibration module 562 (FIG. 32) which is part of the PMCU 128' (FIG. 1and 32), and the plasma monitoring module 560 (FIGS. 32 and 37). Thespectrometer assembly 712, CCD array 716, and calibration light source728 are the same in relation to the similarly identified components ofthe FIG. 31 embodiment. Consequently, the plasma monitoring assembly 700of FIG. 37 differs from the plasma monitoring assembly 500 of FIG. 31principally in relation to the optical arrangement of the calibratingcomponentry.

One function of the calibration assembly 726 is to determine the effect,if any, that the inner surface 40 of the window 38 is having on thelight being emitted from the processing chamber 36. The calibrationassembly 726 also addresses the presence of the outer surface 42 of thewindow 36. As illustrated in FIGS. 37-38, the window 38 on theprocessing chamber 36 includes an inner surface 40 and outer surface 42which are disposed in substantially parallel relation (as illustrated inFIGS. 1 and 6). In order to reduce the effects that light reflected bythe outer surface 42 will have on the calibration module 562, thecalibration assembly 726 uses a fiber optic cable 704 to operativelyinterface the calibration light source 728 and the window 38, andanother fiber optic cable 708 to operatively interface the window 38 andthe spectrometer assembly 712. The fiber optic cable 704 is disposed tohave light from the calibration light source 728 impact the outersurface 42 of the window 38 at an angle other than perpendicular, andthe fiber optic cable 708 is disposed to receive only that portion ofthe calibration light which is reflected by the inner surface 40 of thewindow 38 and not any light which is reflected by the outer surface 42of the window 38. This is illustrated in FIG. 38 where the axis 732corresponds with the orientation of the light from the calibration lightsource 728 as it impacts the window 38, where the axis 736 correspondswith that portion of the calibration light which will be reflected bythe outer surface 42 of the window 38, and where the axis 740corresponds with that portion of the calibration light which will bereflected by the inner surface 40 of the window 38 (refraction not beingshown). In one embodiment, the angle a between the axis 732 and theouter surface 42 of the window 38 ranges from about 10° to about 70°,the angle α between the axis 740 and the inner surface 40 of the window38 ranges from about 10° to about 70°, and the axes 736 and 740 areoffset by an amount ranging from about 2 mm to about 20 mm.

The above-noted relative positioning of the inner surface 40 of thewindow 38, the outer surface 42 of the window 38, the fiber optic cable704, and the fiber optic cable 708 has the effect of having that portionof the calibration light, which is reflected by the outer surface 42 ofthe window 38, be reflected in a manner so as to not enter the fiberoptic cable 708. Therefore, when a calibration light is sent from thecalibration light source 728 to the window 38 through the fiber opticcable 704, the only significant portion of light which the fiber opticcable 708 "sees" is the light which is reflected by the inner surface 40of the window 38--not light from the outer surface 42 of the window 38.The inner surface 40 of the window 38 is that which is affected byconducting plasma processes within the processing chamber 36, and whichthereby affects the light which is emitted from the processing chamber36 through the window 38. Therefore, the light received by thespectrometer assembly 712 during calibration operations by the windowmonitoring assembly 700 presents a more accurate depiction of thecondition of the inner surface 40 of the window 36.

Further enhancement of the arrangement presented in FIG. 37 may berealized by incorporating a broad band anti-reflection coating (e.g., ofmultiple-layer or laminated construction) on the outer surface 42 of thewindow 38 at least in that region where the calibration light impactsthe outer surface 42. These types of coatings increase the amount of thecalibration light which passes through the outer surface 42 of thewindow 38 to the inner surface 40 by reducing the amount of thecalibration light which is reflected by the outer surface 42. In fact,the embodiment presented in FIG. 31 could be used with the type ofwindow presented in the FIG. 37 embodiment where the above-noted coatingis included on the window 38 and with the ends of the fiber optic cableassembly 504 projecting toward the window 38 to form at least asubstantially perpendicular angle relative to both the outer surface 42and the inner surface 40. This arrangement is less preferable in thatnotwithstanding the presence of an anti-reflection coating on the outersurface 42 of the window 38, some portion of the calibration light willstill be reflected back toward the inner cables 508 of the fiber opticcable assembly 504 in this variation (not shown). There will thereby besome interference with that portion of the calibration light which isreflected by the inner surface 40 of the window 38 back to the innercables 508.

Maintaining a proper relative positioning between the fiber optic cable704, the fiber optic cable 708, and the window 38 on the chamber 36 withthe FIG. 37 embodiment is important to the operation of not only thecalibration module 562, but the current plasma process module 250 aswell. One way of interconnecting the foregoing is illustrated in FIG. 39in the nature of a fixture assembly 1564. The fixture assembly 1564includes a window fixture 1568 which securely retains the window 38 andallows for interconnection of the same with the processing chamber 36(e.g, via one or more threaded fasteners). A cavity or recess 1572exists within an interior portion of the window fixture 1568 andinterfaces with the outer surface 42 of the window 38.

The fixture assembly 1564 also includes a fiber fixture 1576 which isappropriately interconnected with the window fixture 1568 (e.g., via oneor more threaded fasteners). The recess 1572 in the window fixture 1568is thereby a closed space in the assembled condition via the outersurface 42 of the window 38 and a portion of the back side of the fiberfixture 1576. Each of the fiber optic cables 704 and 708 are removablyinterconnected with the fiber fixture 1576. A fiber fixture coupling1580b on the fiber fixture 1576 is disposed in the proper orientationfor establishing an appropriate interconnection with the fiber opticcable 704 from the calibration light source 704, while a fiber fixturecoupling 1580a on the fiber fixture 1576 is disposed in the properorientation for establishing an appropriate interconnection with thefiber optic cable 708 leading to the spectrometer assembly 712. The endsof the fiber optic cables 704 and 708 project toward the outer surface42 of the window 38 at the proper angle and in axial alignment with aport 1584a and 1584b, respectively. The ports 1584a and 1584b eachextend through the fiber fixture 1576 to intersect the recess 1572 inthe window fixture 1568. Therefore, calibration light from thecalibration light source 728 is directed through the fiber optic cable704, through the port 1584b in the fiber fixture 1576, through therecess 1572 in the window fixture 1568, and to the outer surface 42 ofthe window 478. Calibration light which is reflected by the innersurface 40 of the window 38 travels through the recess 1572 in thewindow fixture 1568, through the port 1584a in the fiber fixture 1576,into the fiber optic cable 708, and to the spectrometer assembly 712.The particular manner in which calibration operations are undertakenusing the foregoing arrangement is addressed in relation to thecalibration module 562 of FIGS. 40-48.

Calibration Module 562--FIGS. 40-48

Both the calibration assembly 552 of FIG. 31 and the calibrationassembly 726 of FIG. 37 include the calibration module 562 which isillustrated in FIG. 40. This module 562 may be used to calibrate theoutput from each of the spectrometer assembly 506 of FIG. 31 and thespectrometer assembly 712 of FIG. 37. For convenience, the discussionwill continue with regard to only the spectrometer assembly 506 of FIG.31, although such will be equally applicable to the spectrometerassembly 712 of FIG. 37 as well.

Output from the spectrometer assembly 506 may have a tendency to "drift"over the life of the spectrometer assembly 506 due to various factorssuch as temperature. Any drifting of the output from the spectrometerassembly 506 will cause a wavelength shift in the spectra which isevaluated by the current plasma process module 250. An example ofdrifting would be that a peak in a spectra from the processing chamber474 which is actually at the 490 nanometer wavelength, may appear at the491 nanometer wavelength from the output of the spectrometer assembly506 due to this drifting. Moreover, the window 478 may have an effect onthe spectra of the plasma from the current plasma process which ispassing through the window 474 to the spectrometer assembly 506, namelyby providing an intensity shift in one or more regions of the spectrarepresentative of the plasma in the processing chamber 474. Failure toaddress either of these conditions may adversely affect the performanceof the current plasma process module 250.

One embodiment of the calibration module 562 of FIG. 32 is presented inmore detail in FIG. 40 and accounts for both the wavelength andintensity shift conditions noted above. The calibration module 562includes a calibration routine 564 which is run without any plasma inthe processing chamber 474 and which is run at times determined by thefacility using the wafer production system 2 (e.g., once a day, on everyshift change). Instructions may be included in the calibration routine564 to detect the existence of plasma in the processing chamber 474 inany of the above-noted manners, and to exit the calibration routine 564if any such plasma is detected (not shown). Step 568 of the calibrationroutine 564 directs the calibration light source 556 to send thecalibration light to the window 478. Thereafter, step 572 directs thecalibration routine 564 to proceed to an appropriate calibrationsubroutine.

The calibration subroutine referred to in step 572 of FIG. 40 mayinclude the calibration subroutine 576 which is illustrated in FIG. 41.Generally, the calibration subroutine 576 is directed toward making atleast one adjustment in relation to the spectrometer assembly 506 tocompensate for a wavelength shift associated with the spectral dataobtained through the window 478. A comparison is undertaken by step 580of the calibration subroutine 576 between the spectra of the calibrationlight from the calibration light source 556 which is directed to thewindow 478 and the spectra of the calibration light which is reflectedfrom the inner surface 482 of the window 478 and provided to thespectrometer assembly 506. Since no plasma exists in the processingchamber 474 during calibration operations, the light received by thespectrometer assembly 506 should be limited to that portion of thecalibration light which is reflected by the inner surface 482 of thewindow 478 which is therefore a direct monitoring of a condition of thewindow 478, specifically its inner surface 482. Any wavelength shiftfrom the comparison of step 580 will be noted in step 584 of thecalibration subroutine 576, an adjustment will be made in relation tothe plasma monitoring assembly 500 to account for this shift at step 588of the subroutine 576, and control of the plasma monitoring operationswill be turned over to the startup module 202 of FIG. 32 by step 592 ofthe calibration subroutine 576.

The comparison of the subject spectra at step 580 of the calibrationsubroutine 576 and the identification of any wavelength shift in step584 of the subroutine 576 may be implemented in the following manner.The spectra of the calibration light which is sent to the window 478 maybe obtained from the calibration light subdirectory 310 of FIG. 9. Thisspectra is analyzed to identify the location of one or more of theintensity peaks in this spectra and possibly the relative wavelengthpositioning of these intensity peaks. A "peak" may be equated as anyportion of the spectra with an intensity greater than a predeterminedamount (e.g., at least about 100 intensity units) which exists over apredetermined wavelength range (e.g., no more than about 2 nanometers).Therefore, the above-referenced analysis of the spectra of calibrationlight sent to the window 478 may simply entail noting the intensity overat least a portion of this spectra using an appropriate wavelengthresolution. For example, one or more peaks in this spectra may beidentified by noting the intensity of the spectra of the calibrationlight from the calibration light subdirectory 310 at every 0.5 nanometerincrement over at least a portion of this spectra to identify anyintensity peaks as defined above. After identifying these peaks, it maybe beneficial to then note their relative wavelength positionings.

Any intensity peaks in the calibration light which is sent to the window478 which are identified in the above-noted manner should appear at thesame wavelength and "same" intensity level (taking into considerationcertain principles of optics noted below and assuming that there is nointensity shift due to the window 478 also noted below) in that portionof the calibration light which is reflected by the inner surface 482 ofthe window 478 if there is no wavelength shift. Since the location andintensity of one or more peaks was noted for the calibration light thatwas sent to the window 478, the amount of wavelength shift may beidentified simply by finding these same peaks in the portion of thecalibration light that is reflected by the inner surface 482 of thewindow 478 and noting any corresponding wavelength shift. Although theintensity of the peaks alone may be sufficient to identify thecorresponding peaks in that portion of the calibration light that isreflected by the inner surface 482 of the window 478 (e.g., by lookingfor the largest peak around a certain wavelength), the relativepositioning of the identified peaks may be desirable/required in somecases.

The wavelength shift concept addressed in relation to the calibrationsubroutine 574 of FIG. 41 is further addressed in relation to FIGS.42-43. One embodiment of a spectra 672 of a calibration light which isappropriate for identifying a wavelength shift is illustrated in FIG.42, and this calibration light may be used by the calibration lightsource 556 of the calibration assembly 552 (FIG. 31) and by thecalibration subroutine 576 of FIG. 41. The spectra 672 is characterizedby a plurality of discrete intensity peaks 674 of varying intensitywhich is desirable for detecting a wavelength shift, and in oneembodiment is from a mercury light source and comprises the above-notedfirst calibration light source 556a. Other light sources having thesecharacteristics may be utilized as well. "Intensity" is plotted alongthe "y" axis and is expressed in "counts" which is reflective of theintensity level, while "wavelength" is plotted along the "x" axis and isillustrated in nanometers. FIG. 42 depicts the actual pattern ofcalibration light which is sent to the window 478 in the subjectexample. One embodiment of a spectra 676 which is output by thespectrometer assembly 506, due to a reflection of the calibration lightrepresented in FIG. 42 from the inner surface 482 of a "clean" window478 on the processing chamber 474, is presented in FIG. 43 (when thewindow 478 has not yet been exposed to any plasma processes). Thespectra 676 is characterized by a plurality of peaks 678 of varyingintensity, with "intensity" again being plotted along the "y" axis andexpressed in "counts" which is reflective of the intensity level, andwith "wavelength" again being plotted along the "x" axis in nanometers.

Initially, the comparison of the spectra 672 of FIG. 42 with the spectra676 of FIG. 43 indicates that their respective intensities vary rathersignificantly. This is due to certain principles of optics. Generally,materials which would typically be used to form the window 478 willreflect about 6% of the calibration light which is directed toward thewindow 478. More specifically, 6% of the calibration light which isoriginally sent to the window 478 from the calibration light source 556will be reflected by the outer surface 486 of the window 478 along theaxis 494 illustrated in FIG. 35, and the remaining 94% of the light willcontinue through the window 478. When this light encounters the innersurface 482 of the window 478, 6% of this light will be reflected by theinner surface 482 back toward the outer surface 486, and the remaining94% of this light will then enter the processing chamber 474 (i.e.,5.64%). This light reflected by the inner surface 482 will once againhit the outer surface 486 which will reflect 6% of this light backtoward the chamber 474, while 94% will pass through the outer surface486. Therefore, only about 5.3% of the light originally sent by thecalibration light source 445 for calibration of the output of thespectrometer assembly 506 will actually enter the inner cables 508 ofthe fiber optic cable assembly 504 and be provided to the spectrometerassembly 506. This principle of optics thereby accounts for thedifference in intensity between the spectra 676 of FIG. 43 and thespectra 672 of FIG. 42, and would have to be taken into account in thecalibration procedure.

The spectra 676 of FIG. 43 may be compared with the spectra 672 of FIG.42 in the abovedescribed manner to determine if the output from thespectrometer assembly 506 needs to be calibrated for a wavelength shift.The peaks 678 of the spectra 676 of FIG. 43 should appear at the samewavelengths as the corresponding peaks 674 of the spectra 672 of FIG.43. For example, the peak 678a from FIG. 43 and the peak 674a from FIG.42 should be at the same wavelength, the peak 678b from FIG. 43 and thepeak 674b from FIG. 42 should be at the same wavelength, the peak 678cfrom FIG. 43 and the peak 674c from FIG. 42 should be at the samewavelength, and so forth. In the illustrated example, the correspondingpeaks from the spectras 676 and 672 are properly aligned or are at thesame wavelengths. Therefore, no wavelength shift would be identified bysteps 580 and 584 of the calibration subroutine 576 of FIG. 41.Moreover, with no wavelength shift being identified through execution ofstep 584 of the calibration subroutine 576, no adjustment in relation tothe plasma monitoring assembly 500 is undertaken through execution ofstep 588 of the subroutine 576. Control of the plasma monitoringoperations is then transferred to, for instance, the startup module 202of FIG. 15 by execution of step 592 of the subroutine 576.

Having the peaks of the spectra 672 and 676 be at the exact samewavelength improves the accuracy of the current plasma process module250. If the wavelength shift limit associated with steps 580 and 584 is"0" and if the peaks of the noted spectra are offset by even a smallamount, the adjustment made in relation to the plasma monitoringassembly 500 at step 588 will be correspondingly "small." The amount ofwavelength shift which will initiate an adjustment in relation to theplasma monitoring assembly 500, however, need not be zero. That is, acertain amount of wavelength shift may be tolerated before an adjustmentis made in relation to the plasma monitoring assembly 500 at step 588.For instance, in one embodiment no adjustments are made in relation tothe plasma monitoring assembly 500 unless a wavelength shift of at leasta certain amount is identified by steps 580 and 584 of the subroutine576 (e.g., a wavelength shift of at least about 0.25 nanometers isrequired before any adjustment is made).

If more than the allowed amount wavelength shift is identified in step584 of the calibration subroutine 576 of FIG. 41, as noted step 588 ofthe subroutine 576 provides for the adjustment in relation to the plasmamonitoring assembly 500. At least two options exist for this "making atleast adjustment in relation to the plasma monitoring assembly 500." Onealternative is to physically adjust the spectrometer assembly 506 ifsuch is of the scanning type. FIG. 44 presents one embodiment of thespectrometer 516a' which is of the scanning-type. The spectrometer 516a'includes an aperture 520 through which light from the inner cable 508aof the fiber optic cable 504 assembly enters the spectrometer 516a'.Light passing through the aperture 520 is reflected by a mirror 524 ontoa grating 532. Both the mirror 524 and grating 532 may be mounted forpivotal movement through a mirror pivot 528 and a grating pivot 536,respectively. Movement of the mirror 524 and the grating 532 would beaffected by the motor 540 and the gearbox 544. The motor 540 isoperatively interfaced with the PMCU 128'. Movement of one or more ofthe mirror 524 and grating 532 may be utilized such that the peaks 678of the spectra 676 in FIG. 43 will be appropriately aligned with thecorresponding peaks 674 of the spectra 672 in FIG. 42. Thereafter, thepresence of the wavelength shift being caused by the spectrometerassembly 506 will not adversely affect the reliability of the resultsprovided by the current plasma process module 250 since the wavelengthshift has now been alleviated.

Another way to make the adjustment referred to in step 588 of thecalibration subroutine 576 of FIG. 41 is to "regression fit" the data insome way. This option may be used regardless of what type ofspectrometer is implemented for the spectrometer assembly 506. Considerthe example where the comparison between the spectra 676 of FIG. 43 andthe spectra 672 of FIG. 42 identifies the existence of a wavelengthshift (not shown since the corresponding peaks 674 and 678 are properlyaligned). The output from the spectrometer assembly 506 may beregression fit to account for the noted wavelength shift. It should beappreciated that if a solid state spectrometer assembly 506 is usedwhich is actually multiple spectrometers such as the multiplespectrometers 516 illustrated in FIG. 33, only that portion of thespectra which has shifted due to its associated spectrometer 516 need beregression fit in the above-noted manner.

Information on the presence of any wavelength shift identified by thecalibration subroutine 576 also may be input to the current plasmaprocess module 250, more specifically the pattern recognition module 370of FIG. 13 to account for this wavelength shift when comparing spectrafrom a current plasma processing operation with spectra in the plasmaspectra directory 284. Consider the situation where the 200 nanometerwavelength of the current spectra from the processing chamber 474 isbeing evaluated, and where a 1 nanometer wavelength shift has beenidentified by the calibration assembly 552 at the 200 nanometerwavelength. When looking to compare this data point with spectra in theplasma spectra directory 284, the "inputting" to the pattern recognitionmodule 370 of the 1 nanometer wavelength shift for the 200 nanometerwavelength directs the pattern recognition module 370 to actually lookat the 201 nanometer wavelength of the corresponding spectra in thiscase to determine if the two intensities are within the intensity matchlimit of the pattern recognition module 370. Therefore, the presence ofthe wavelength shift will not adversely affect the reliability of theresults provided by the current plasma process module 250 of FIG. 32.

The calibration assembly 552 of FIG. 31, and including the calibrationmodule 574 of FIG. 40, may also be used to calibrate the output from thespectrometer assembly 506 when there is an intensity shift in thespectra of the plasma in the processing chamber 474. Intensity shifts inthe spectra will typically be due to "aging" of the window 478. "Aging"of the window 478 as used herein means that the plasma processes whichhave been conducted within the processing chamber 474 have affected theinner surface 482 of the window 478 in some manner (e.g., by formingdeposits on the inner surface 482, by etching the inner surface 482, bya combination of forming deposits on and etching the inner surface 482).Oftentimes these deposits will reduce the intensity of the light fromthe chamber 474 which passes through the window 478 and is directed tothe spectrometer assembly 516 (FIG. 31). Failing to account for anintensity shift in the spectra due to the window 478 in these cases mayalso adversely affect the reliability of the results provided by thecurrent plasma process module 250. Consider the situation where thepattern recognition subroutine 374 of FIG. 13 with its point-by-pointanalysis is employed by the pattern recognition module 370 to comparethe pattern of the current spectra with the spectra in the plasmaspectra directory 284 (FIG. 9), and where the intensity "match limit" isset on 10% (a percentage difference basis). Also assume that certaindeposits have formed on the inner surface 482 of the window 478 suchthat the intensity of light emitted through the window 478 is reduced by30%. In this case, even if the plasma in the processing chamber 474 ishealthy, the light that is emitted through the window 478 will only be70% of the actual intensity of the plasma inside the chamber 474. Thepattern recognition subroutine 374 will therefore indicate that thecurrent spectra is not a "match" with any spectra in the relevantsubdirectory of the plasma spectra directory 284 (because its "matchlimit" is a 10% variation in the intensity of corresponding wavelengthsin the subject spectra, and because the window deposits have reduced theintensity of light from the chamber 474 by 30%), even though the plasmais in fact healthy. Therefore, a "false negative" would be reported bythe pattern recognition subroutine 374 and the current plasma processmodule 250.

The calibration module 574 of FIG. 40 may also include a calibrationsubroutine which is generally directed toward making an adjustment toaccount for the above-noted type of intensity shift in the spectra ofthe plasma in the chamber 474 as emitted through its window 478. Oneembodiment of such a subroutine is illustrated in FIG. 45 in the natureof the calibration subroutine 600. No plasma exists in the chamber 474during the execution of the calibration subroutine 600 or at least whenobtaining data therefore. Moreover, detection of plasma in accordancewith the foregoing may automatically terminate calibration operationsthrough the subroutine 600. Finally, the subroutine 600 may be executedon a periodic basis which is established by the operator of the facilityusing the wafer production system 2 (e.g., daily).

A comparison is undertaken at step 604 of the calibration subroutine 600between the spectra of the calibration light from the calibration lightsource 556 which is directed to the window 478 and which may be storedin the calibration light spectra subdirectory 310, and the spectra ofthat portion of the calibration light which is reflected from the innersurface 482 of the window 478 and provided to the spectrometer assembly506. Since there is no plasma in the chamber 474 at this time, the lightprovided to the spectrometer assembly 506 should be limited to thatportion of the calibration light which is reflected by the inner surface482 of the window 478. As such, the calibration subroutine 600 actuallymonitors/evaluates the condition of that portion of the window 478 whichmay be adversely affected by plasma processes conducted in the chamber474.

The comparison of the subject spectra at step 604 of the calibrationsubroutine 600 and the identification of any intensity shift in step 608of the subroutine 600 may be implemented in the following manner. Thespectra of the calibration light which is sent to the window 478 may beobtained from the calibration light subdirectory 310 of FIG. 9. Itsintensity peaks are identified in the manner discussed above in relationto the calibration subroutine 576 of FIG. 41, as well as possibly theirrelative wavelength positionings. These same peaks should appear at thesame wavelength (assuming that there is no wavelength shift) and "same"intensity level (taking into consideration the above-noted principles ofoptics) in that portion of the calibration light which is reflected bythe inner surface 482 of the window 478. Since the location andintensity of one or more peaks was identified for the calibration lightthat was sent to the window 478, the amount of intensity shift may beidentified simply by finding these same peaks in that portion of thecalibration light which is reflected by the inner surface 482 of thewindow 478 and noting any corresponding intensity shift. Although theintensity of the peaks alone may be sufficient to identify thecorresponding peaks in that portion of the calibration light that isreflected by the inner surface 482 of the window 478 (e.g., by lookingfor the largest peak around a certain wavelength), the relativepositioning of the identified peaks may be desirable/required in somecases.

The intensity shift concept addressed in relation to the calibrationsubroutine 600 of FIG. 45 is further addressed in relation to FIGS. 46Aand 47A. One embodiment of a spectra 682 of a calibration light isillustrated in FIG. 46A (e.g., a mercury lamp or other similarcalibration light source with light defined by wavelengths from about200 nanometers to about 1,000 nanometers), and this calibration lightmay be used by the calibration light source 556 of the calibrationassembly 552 (FIG. 31) and by the calibration subroutine 600 (FIG. 45)to identify an intensity shift. The spectra 682 of FIG. 46A ischaracterized by a plurality of discrete intensity peaks 686 of varyingintensity. "Intensity" is plotted along the "y" axis and is expressed in"counts" which is reflective of the intensity level, while "wavelength"is plotted along the "x" axis and is in nanometers. FIG. 46A depicts theactual pattern of light which is sent to the window 478 in the subjectexample and when the window 478 has been exposed to a plurality ofplasma processes (e.g., an "aged" window 478). One embodiment of aspectra 690 which is output by the spectrometer assembly 506 ispresented in FIG. 47A after the above-noted principles of optics hasbeen accounted for and which is representative of that portion of thecalibration light which is reflected from the inner surface 482 of theaged window 478 on the processing chamber 474. The spectra 690 ischaracterized by a plurality of discrete peaks 694 of varying intensity,with "intensity" again being plotted along the "y" axis and expressed in"counts" which is reflective of the intensity level, and with"wavelength" being plotted along the "x" axis in nanometers.

The spectra 690 of FIG. 47A may be compared with the spectra 682 of FIG.46A to determine if the output from the spectrometer assembly 506 needsto be calibrated for an intensity shift, such as due to an aging window478. This comparison is again undertaken at step 604 of the calibrationsubroutine 600 of FIG. 45. The peaks 694 of the spectra 690 of FIG. 47Ashould appear not only at the same wavelengths as the correspondingpeaks 686 of the spectra 682 of FIG. 46A (as discussed above in relationto calibrating the output of the spectrometer assembly 506 for awavelength shift), but they should also be at the same level ofintensity. For example, the peak 694a from FIG. 47A and the peak 686afrom FIG. 46A should be at the same intensity level, the peak 694b fromFIG. 47A and the peak 686b from FIG. 46A should be at the same intensitylevel, the peak 694c from FIG. 47A and the peak 686c from FIG. 46Ashould be at the same intensity level, and so forth. However, this isnot the case.

Peak 694a of the spectra 690 from FIG. 47A is at substantially the sameintensity (about 9300) as its corresponding peak in the spectra 682 ofFIG. 46A, namely peak 686a. However, peak 694b of the spectra 690 fromFIG. 47A has an intensity of about 5,100, whereas the intensity of itscorresponding peak in the spectra 682 from FIG. 46A, namely peak 686b,has an intensity of about 11,100. That is, there was a intensity drop ofabout 6000 intensity units or about a 54% drop in intensity at about the450 nanometer wavelength region. Moreover, peak 694c of the spectra 690from FIG. 47A has an intensity of about 9,600, whereas the intensity ofits corresponding peak in the spectra 682 from FIG. 46A, namely peak686c, has an intensity of about 12,000. That is, there was an intensitydrop of about 2,400 intensity units or about a 20% drop in intensity atabout the 760 nanometer wavelength region. Therefore, the window 478 isnot having the same dampening effect on the entire spectra beingobtained through the window 478. Instead, the window 478 is having atleast a first dampening effect on one part of the spectra (e.g., the 450nm region) and a second dampening effect on another part of the spectra(e.g., the 760 nm region) which is identifiable by comparing thepatterns in the noted manner. Step 612 of the calibration subroutine 600will make at least one adjustment in relation to the plasma monitoringassembly 500 to account for these types of intensity shifts, and thencontrol will be turned over to the startup module 202 of FIG. 32 by step614 of the calibration subroutine 600 of FIG. 45.

The adjustment referred to in step 612 of the calibration subroutine 572may be generally viewed as normalizing the spectra 690 of FIG. 47A(calibration light reflected by the inner surface 482 of the window 478)to the spectra 682 of FIG. 46A (calibration light sent by thecalibration light source 556 to the window 478). One way of"normalizing" the data is by "regression fitting." This option may beused regardless of what type of spectrometer is implemented for thespectrometer assembly 506, such that this option may be employed forboth scanning-type spectrometers and solid state spectrometers. Anotherway of characterizing the subject adjustment is through the concept ofcalibration factors or gain. If there is a "uniform" intensity shift,one calibration factor or gain may be applied to the optical emissionsdata which is collected on the current plasma process. Multipledampening effects identified in accordance with the foregoing may thenbe addressed through multiple calibration factors or gains. One or moreparts of the spectra of reflected light may require the application ofone calibration factor or gain thereto, while one or more parts of thesubject spectra may require the application of another calibrationfactor or gain thereto, and so forth. Finally, the spectrometer assembly506 may be manipulated in some manner to obtain more light, althoughsuch is not as preferred as the foregoing.

Consider the example where the comparison between the spectra 690 ofFIG. 47A and the spectra 682 of FIG. 46A indicates the existence of anintensity shift. The output from the spectrometer assembly 506 may beregression fit to account for the intensity shift which was identified.Alternatively, information on the presence of this intensity shift maybe input to the current plasma process module 250, more specifically thepattern recognition module 370 of FIG. 13, to account for this intensityshift when comparing spectra from a current plasma process with spectrain the plasma spectra directory 284.

Limits may be utilized for adjustments made in relation to the plasmamonitoring assembly 500 by any of the calibration subroutines notedherein. For instance, in the event that the amount of calibration orgain required to address an intensity shift exceeds a first limit (or awavelength shift for that matter), a message may be displayed to theappropriate personnel that the window 478 has degraded or aged to thedegree where the accuracy of the results provided by the plasmamonitoring assembly 500 may be affected to an undesirable degree.Alternatively, exceeding this first limit may in fact disable the plasmamonitoring assembly 500 and a corresponding indication may be providedto operations personnel. Imposing a nigher limit than the noted firstlimit may also be used to trigger disabling of the plasma monitoringassembly 500 (i.e., warn when a first limit is exceeded, and disablewhen a second, higher limit is exceeded).

The calibration light illustrated in FIG. 46A and discussed above has aplurality of discrete intensity peaks. Therefore, only 31 data pointsmay be evaluated by the subroutine 600 of FIG. 45 to identify the effectthat the window 478 is having on the optical emissions passingtherethrough (i.e., there are only 31 intensity peaks, and the remainderis merely noise). Assumptions would have to be made as to the effectthat the window 478 is having on optical emissions at those wavelengthsbetween these peaks. An embodiment of a calibration light which may beused by the calibration light source 556 (FIG. 31) and the calibrationsubroutine 600 (FIG. 45) to identify an intensity shift, whichalleviates the need for these types of assumptions, is presented in FIG.46B. The calibration light of FIG. 46B is of a different type than thatillustrated in FIG. 46A in that the calibration light of FIG. 46Bpresents a continuum of intensity, while the calibration light of FIG.46A has a plurality of discrete intensity peaks. This light may be thesecond type used by the second calibration light source 556b noted above(the first type being the calibration light of FIG. 42/46A to identify awavelength shift). In one embodiment, the calibration light foridentifying an intensity shift is a white light source defined bywavelengths which include at least the Preferred Optical Bandwidth.Therefore, the calibration light source 556 may actually include onetype of light source for identifying a wavelength shift (e.g., FIG.42/46A), and may use a different light source for identifying anintensity shift (e.g., FIG. 46B).

The comparison of the spectra 666 of FIG. 46B (calibration light sent tothe window 478) with the spectra 670 of FIG. 47B (that portion of thecalibration light which is reflected by the inner surface 482 of thewindow 478 and provided to the spectrometer assembly 506) may be done inthe same manner as discussed above in relation to FIGS. 46A and 47A.However, a more complete "picture" of the behavior of the window 478 isprovided by using a calibration light having a continuum of intensitysince there are more data points available for comparison than in thecase of a spectra which only has a plurality of intensity peaks witheffectively "noise" therebetween (e.g., FIG. 42/46A). Moreover, acomparison of the spectra 666 of FIG. 46B and the spectra 670 of FIG.47B indicates how the window 478 is having a different effect ondifferent portions of the spectrum. Note how the shapes of the spectra666 and the spectra 670 are generally the same between about the 200 nmand 575 nm wavelengths although with different intensities, but how theshapes of the spectra 666 and the spectra 670 differ between about the575 nm and 950 nm wavelengths. Specifically, the profile of the spectra670 of FIG. 47B between about the 575 nm and 950 nm wavelengths is"flatter" than the corresponding portion of the spectra 666 of FIG. 46B.Therefore, the window 478 is having one type of effect on opticalemissions generally between about the 200 nm and 575 nm wavelengthregion, and another different effect on optical emissions generallybetween about the 575 nm and 900 nm wavelength region.

Another embodiment of a calibration subroutine which may be utilized bythe calibration module 574 of FIG. 40 is illustrated in FIG. 48. Thecalibration subroutine 616 is able to identify when the window 478 ishaving different dampening effects on different portions of the spectraldata being emitted through the window 478. Moreover, the subroutine 616is also able to identify when the window 478 is completely filtering yetdifferent portions of the spectral data being emitted through the window478. Preferably, the calibration subroutine 616 uses a light sourcewhich has a continuum of intensity to provide these functions, such asthe light source depicted in FIG. 46B.

Referring now to FIG. 48, the calibration subroutine 616 starts withstep 620 which initiates a comparison between the spectra of thecalibration light which is sent by the calibration light source 556 tothe window 478 (hereafter "reference spectra" for purposes of thesubroutine 616) (e.g., FIG. 46B), and the spectra of that portion of thecalibration light which is reflected by the inner surface 482 of thewindow 478 (hereafter "reflected spectra" for purposes of the subroutine616) (e.g., FIG. 47B). Any "change" in intensity between the referencespectra and the reflected spectra is noted at step 624 of thecalibration subroutine 616. Steps 620 and 624 may employ the same typeof logic as presented by steps 580 and 584 of the calibration subroutine576 of FIG. 41 and steps 604 and 608 of the calibration subroutine 600of FIG. 45. The "change" in intensity referenced in step 624 of thecalibration subroutine 616 of FIG. 48 may be a predefined tolerance or a"match limit" as discussed above in relation to the pattern recognitionmodule 370 of FIG. 13. That is, if each "point" of the reflected spectrais within the "match limit" of the corresponding "point" in thereference spectra, the calibration subroutine 616 will proceed to step628. Step 628 indicates that no calibration of the plasma monitoringassembly 500 is required, and that the control is passed to the startupmodule 202 of FIG. 15.

If there is a "change" in intensity between the reflected spectra andthe reference spectra (e.g., exceeding the "match limit" in thecomparison of the reflected spectra and reference spectra at one or morepoints in the point-by-point analysis), the calibration subroutine 616will proceed from step 624 to step 632. Step 632 analyzes the manner inwhich the reflected spectra differs from the reference spectra inrelation to the subject intensity criteria. If there was a "uniform"intensity shift of the reflected spectra in relation to the referencespectra, the calibration subroutine 616 proceeds to step 636 where asingle calibration factor or uniform gain is applied to the entirety ofthe reflected spectra (and thereby to optical emissions data obtainedduring a current plasma process) to "normalize" the same to thereference spectra. Control is then transferred to the startup module 202of FIG. 15 via step 640 of the calibration subroutine 616. "Uniform" inrelation to step 632 of the calibration subroutine 616 need not belimited to a fixed number of intensity units (e.g., the entirety of thereflected spectra need not differ from the entirety of the referencespectra by the same amount), but instead may utilize a raw difference, apercentage difference, or a combination thereof as the "match limit" asthose terms are used in relation to the pattern recognition module 370of FIG. 13. For instance, any change in intensity between eachwavelength in the reflected spectra which is within ±5% of the intensityof the corresponding wavelength in the reference spectra may beconsidered a "uniform" intensity shift for purposes of step 632 of thecalibration subroutine 616.

If the comparison between the reflected spectra and the referencespectra at step 632 of the calibration subroutine 616 indicates thatthere is not a "uniform" intensity shift of the reflected spectra inrelation to the reference spectra, the subroutine 616 proceeds from step632 to step 644. Generally, step 644 is directed to determining if thereis any evidence of complete filtering of data over any wavelength rangewithin the reflected spectra. Under certain conditions, the innersurface 482 of the window 478 may be affected such that light emissionsover a certain wavelength range will be completely blocked (e.g., thewindow 478 will become opaque over this wavelength range which would beevident by an effectively horizontal line in the subject spectra at arelatively low intensity and including a zero intensity level). Anexample would be where the window 478 is opaque in relation to lightemissions over the wavelength range of about 300-400 nanometers, but istransparent to at least a degree over other wavelengths of light beingcollected and provided to the spectrometer assembly 506 (FIG. 31).

Any "complete filtering" of any wavelength range in the reflectedspectra as discussed herein will cause the calibration subroutine 616 toproceed from step 644 to step 648. Data within the completely filteredregion is ignored in any analysis subsequently provided by the currentplasma process module 250 of FIG. 32 as set forth in step 648 of thecalibration subroutine 616. Moreover, at least two different calibrationfactors are applied to different portions of the remainder of the datain the reflected spectra as set forth in this same step 648, or thereflected spectra is normalized in relation to the reference spectraover that portion which is not being filtered. Again recall that it wasdetermined that the intensity shift in the reflected spectra, inrelation to the reference spectra, was "non-uniform" in step 632 of thesubroutine 616 such that the application of a single calibration factorto the reflected spectra would not be appropriate to "normalize" thereflected spectra in relation to the reference spectra in this case.

As noted, the analysis of any plasma process thereafter performed whichis analyzed by the current plasma process module 250 will be limited toonly part of the desired optical emissions data. Data within thewavelength region which is being completely filtered by the window 478is ignored. As such, the calibration subroutine 616 may be programmed toproceed from step 648 to the process alert module 428 of FIG. 14 aswell. One or more alerts may be issued through the process alertsubroutine 432. For instance, it may be appropriate to appriseoperations personnel at this time that the window 478 is aging andshould be replaced, that the results provided by any further executionsof the current plasma process module 250 may provide inaccurate resultssince certain data from the current plasma process will be ignored inthe comparative analysis, or both. Alternatively and if desired by theoperator of the facility incorporating the wafer production system 2,any exiting of step 644 of the calibration subroutine 616 as a "yes"condition may call upon the process alert module 428 to terminate allfurther plasma processing operations until the window 478 is replaced(not shown).

Control of the calibration subroutine 616 of FIG. 48 may pass from step644 to step 656 if there was no complete filtering of data in thereflected spectra. Calibration of the reflected spectra pursuant to step656 would then entail the application of at least two differentcalibration factors or a plurality of gains throughout the reflectedspectra, or alternatively the normalization as discussed above. Againrecall that it was determined in step 632 that the intensity shift inthe reflected spectra in relation to the reference spectra wasnon-uniform such that application of a single calibration factor wouldnot be appropriate to "normalize" the reflected spectra to the referencespectra. In the case of step 656, one calibration factor may be appliedto the reflected spectra over the 200 nanometer to 500 nanometerwavelength region, while a different calibration factor may be appliedto reflected spectra over the 501-900 nanometer wavelength region.Calibration subroutine 616 then exits step 656 to step 660 where controlmay be transferred to, for instance, the startup module 202 of FIG. 15.

The calibration subroutine 616 of FIG. 48 may be characterized asmonitoring the window 478, and based upon these results specifying howsubsequent plasma processes should be evaluated. If the monitoring ofthe condition of the window 478 through the subroutine 616 determinesthat there is no significant dampening of optical emissions from thechamber 474 through the window 478 or there is only dampening and notany complete filtering, the calibration subroutine 616 provides thatplasma monitoring operations proceed normally by comparing the"normalized" output from the spectrometer assembly 506 with spectra inthe plasma spectra directory 284. Situations where some dampening of theoptical emissions from the chamber 474 through the window 478 and wheresome complete filtering of spectral data over a certain wavelength rangeis identified by execution of the calibration subroutine 616 dictatesthat a different evaluation technique be utilized. Specifically, some ofthe desired data is ignored in the analysis.

Research Module 1300--FIGS. 49-51C

All of the evaluations described so far in relation to the currentplasma process module 250 of FIGS. 7 and 32 have related in one manneror another to the "health" of the plasma process. Another type ofevaluation which is available through the current plasma process module250 relates to the endpoint of a plasma process or a certain portionthereof. Plasma cleans, conditioning wafer operations, and each step ofa plasma recipe (whether run on a qualification wafer 18 or a productionwafer 18) each will typically have an endpoint associated therewith(when the intended/predetermined result has been achieved, such as thecomplete removal of a layer of material in a plasma etch) which willtypically be reflected in the optical emissions of the plasma in thechamber 36 and which thereby may be used to call "endpoint." Thefollowing will discuss endpoint in relation to a plasma step of a plasmarecipe run on a production wafer 18, although it is equally applicableto any plasma process having one or more endpoints, including withoutlimitation those identified above.

One way of identifying endpoint through the current plasma processmodule 250 for a given plasma step requires that some analysis beundertaken of at least one previous execution of this same plasma stepin the same processing chamber 36. In this regard, the current plasmaprocess module 250 includes a research module 1300 which is a submodulethereof and which is presented in FIG. 49. The research module 1300includes a research subroutine 1478 which is run to identify whichcharacteristic(s) of those optical emissions of the plasma in theprocessing chamber 36 may be indicative of the endpoint of the subjectplasma step, and which may then be used by the endpoint detection module1200 of FIGS. 7 and 32 to identify the occurrence of the endpoint of thesubject plasma step.

The research module 1300 may be accessed through the startup module 202of FIG. 15 through execution of steps 144 and 148. The researchsubroutine 1478 of FIG. 49 typically is set to evaluate multipleexecutions of the same plasma step and identifies the optical emissionsdata of the plasma in the chamber 36 which may be used to call endpoint.Some information about endpoint may be obtained by looking at theoptical emissions data from only a single run. The research subroutine1478 of FIG. 49 utilizes, but does not necessarily require, someknowledge of the plasma step, such as a time estimate of the length oftime required to reach the endpoint of the plasma step. In oneembodiment, this a priori knowledge may be used such that opticalemissions data is obtained on the plasma step at a point in time whichshould include this endpoint. In this regard, a time estimate t_(e) forcompleting the subject plasma step (reaching its endpoint) is input tothe subroutine 1478 by execution of step 1480. This time estimate forreaching endpoint may be calculated based upon, for instance, knowingthe etch rate of the subject process and the thickness of the layer tobe etched away. Another way of identifying a time associated with thesubject endpoint uses the data on the current plasma process. In thisregard, each time optical emissions are obtained for the subroutine 1478(e.g., over the Preferred Optical Bandwidth and at the Preferred DataResolution), the total intensity of these optical emissions iscalculated by adding the intensity of each individual wavelength inthese optical emissions. Any time there is a significant change in theabove-noted sum between two adjacent-in-time optical emissions may beindicative that endpoint occurred at that time.

Step 1490 of the subroutine 1478 directs that product be loaded into theprocessing chamber 36 and step 1482 directs that the plasma stepthereafter be initiated by the introduction of plasma into theprocessing chamber 36 under the appropriate conditions to initiate thedesired plasma step. Optical emissions of the plasma in the processingchamber 36 during the plasma step are obtained for the subroutine 1478at a current time t_(c) for the subroutine 1478 through execution ofstep 1484, preferably using the Preferred Optical Bandwidth at thePreferred Data Resolution. Adjustment of the "clock" of the subroutine1478 occurs at step 1486 where the current time t_(c) is increased by anincrement of "n." Preferably, "n" is set at the Preferred DataCollection Time Resolution. If the new current time t_(c) is less than apreset value relating to the time estimate t_(e), step 1488 of thesubroutine 1478 causes the subroutine 1478 to exit step 1488 and returnto step 1484 for repetition in accordance with the foregoing. Althoughthe "preset value" referred to in step 1488 may be the time estimatet_(e) from step 1480, it may be desirable to use a larger value toensure that optical emissions data is obtained for the time whenendpoint of the plasma step is actually reached. Another way ofcharacterizing the foregoing is that optical emissions data should berecorded until the plasma goes off in the chamber 36 to be able toidentify one or more wavelengths which may be indicative of endpoint.

Steps 1484,1486, and 1488 of the research subroutine 1478 are basicallydirected to obtaining optical emissions data of the entirety of thesubject plasma step within the Preferred Data Collection Bandwidth, atthe Preferred Data Resolution, and at the Preferred Data Collection TimeResolution. This data could be analyzed at this time to identifycharacteristics in the optical emissions data which are candidates forbeing an indicator of endpoint. Preferably, however, data is obtained inaccordance with the foregoing on multiple executions of this same plasmastep in the same processing chamber 36. This is implemented throughexecution of step 1492 of the subroutine 1478 which directs that theforegoing be repeated for the desired amount of executions of the plasmastep (at least 2 runs). Once the desired amount of data is obtained (thedesired number of runs), the data is analyzed through execution of step1496 of the research subroutine 1478 to identify that optical emissionsdata or a portion thereof which may be used as an indicator of endpoint.This analysis is currently done manually.

The analysis referred to in step 1496 of the research subroutine 1478may be generally directed to identifying those optical emission lines(e.g., individual wavelengths) which undergo some type of a recognizableor discernible change around the time that the endpoint of the plasmastep is supposed to have occurred. One type of change which would make aparticular wavelength a possible candidate for being an indicator ofendpoint is illustrated by a review of the optical emissions datapresented in FIGS. 50A-C. Each of these figures represents a plot ofintensity versus time through a time which should include the endpointof the subject plasma step for three specific wavelengths λ₁, λ₂, andλ₃. The plots were generated from optical emissions data which wasobtained from one execution of the subject plasma step on a wafer 18 inthe processing chamber 36. Preferably, a plot of this type is obtainedfor each wavelength of light which is obtained based upon the opticalresolution being used in collecting the optical emissions data.

An examination of FIG. 50A for the wavelength λ₁ from this first runningof the plasma step reveals that there is no real discernible change atany time during the plasma step. That is, the line for wavelength λ₁ isat least substantially horizontal in FIG. 50A. However, the plot for thewavelength λ₂ in FIG. 50B reveals two distinct changes in its emissionsline. One change occurs at about the 15 second mark, while anotherchange appears at about the 40 second mark. The plot for the wavelengthλ₃ of FIG. 50C also has two distinct changes in its emissions line. Onechange occurs at about the 20 second mark, while another change appearsat about the 40 second mark. Therefore, although the wavelength λ₁ canbe ruled out as not being indicative of endpoint for the subject stepsince there is no discernible change in its entire emissions line overthe relevant time period, both the wavelengths λ₂ and λ₃ remaincandidates for being endpoint indicators because they each have at leastone distinct change in their respective emission lines.

Having some knowledge of the plasma step, such as a time estimate of itsendpoint, may eliminate some of the wavelengths of data obtained on thesubject plasma process, some of the changes which occur in the plot fora particular wavelength, or both. For instance, if the time estimate forreaching endpoint of the subject plasma step was somewhere around 40seconds, the changes which occurred at the 15 and 20 second timeintervals in the intensity versus time plots for the wavelengths λ₂ andλ₃, respectively, could be eliminated due to their temporal spacing fromthe time estimate for endpoint. However, both of the wavelengths λ₂ andλ₃ would still be candidates for being an indicator of endpoint becausethere is a change in each of these plots at about the 40 second mark. Nodefinitive determination should be made at this point without obtainingadditional data in the nature of data on another running of the plasmastep in the same processing chamber 36. It is important to note that allchanges in the plasma are important in monitoring the plasma health andshould be noted, even though they may be ignored in relation toestablishing an endpoint indicator(s).

FIGS. 51A-C present the optical emissions data for the same wavelengthsλ₁, λ₂, and λ₃ that are presented in FIGS. 50A-C, but from anotherrunning of the same plasma step in the processing chamber 36. The plotof the wavelength λ₁ in FIG. 51A still indicates that nothing aboutendpoint can be derived from this wavelength λ₁. The plot for thewavelength λ₂ in FIG. 51 B is at least substantially the same aspresented in FIG. 50B. The two distinct changes in its emissions linemay be due, for instance, to certain changes in the process such as theopening/closing of a valve(s). Although the plot for the wavelength λ₃in FIG. 51C has the same general pattern, the two distinct changes occurabout 5 seconds later than they did in the run depicted in FIG. 50C.This may be an indication that the wavelength λ₃ is reflective of theendpoint of the subject plasma step where endpoint may vary in time bysome acceptable time differential.

Summarizing the foregoing, wavelengths which may undergo a change whichcorresponds with endpoint of the subject step may be identified bycomparing the plots of the various wavelengths from run to run andidentifying those patterns which are generally the same from run to run,but which have some type of change. For instance, this change may be oneor more of a temporal shift, an intensity shift, an expansion of thepattern, and a reduction in the pattern. These types of changes may bedue to factors which vary from run to run, such as the thickness of thelayer which is being addressed by the plasma step which may cause atemporal shift. Therefore, one way to to identify a particularwavelength which is indicative of endpoint is to run the same plasmastep on multiple products, each having a different thickness of thelayer to be etched away such that the time at which endpoint will occurwill also vary. Wavelengths which have changes which may indicative ofendpoint are those where the subject change ("around" endpoint) alsoshifts in time.

Once the wavelength(s) changes that are potentially indicative ofendpoint are identified through the research module 1300, an endpointdetection technique is still required to use this information toidentify endpoint. One such techniques entails defining the pattern ofthat portion of the plot of intensity versus time for the subjectwavelength(s) up to where the change occurred which was selected asbeing indicative of endpoint. Definition of this portion of the plot maybe through an equation or a function (e.g., linear function, first orderpolynomial, second order polynomial). Endpoint may then be deemed tohave been reached for subsequent executions of this same plasma stepwhen the corresponding wavelength(s) no longer fits the equation orfunction. Another option is to take the first or second derivative ofthis function to identify the slope of the resulting line. The change inslope over time of the current optical emissions data may be plotted.Endpoint may be called when this plot deviates by more than apredetermined amount from that identified by the first or secondderivative of the subject function.

There are other ways of characterizing which wavelength(s) may providesome type of indication that endpoint has been reached from the opticalemissions data collected on the current plasma process. The opticalemissions data obtained for the research subroutine 1478, morespecifically the plot of intensity versus time, may be reviewed toidentify a peak which changes throughout the process and then reaches asteady state at about the time that endpoint is to have occurred.Moreover, these plots may be reviewed to identify a peak which remainsat a steady state for the process and then begins to change at about thetime that endpoint is to have occurred. A small subset of this behaviorincludes behavior in which a suspect wavelength or wavelengths diminishto background or a new wavelength appears at about a time where endpointwas suspected to occur.

Endpoint Detection Module 1200--FIGS. 52-58

The actual detection of the endpoint of a plasma process (e.g., plasmaclean, conditioning wafer operation) or discrete portion thereof (e.g.,one or more steps of a plasma recipe; all steps of a multi-step plasmarecipe) is realized through use of the current plasma process module 250of FIGS. 7 and 32, and more specifically through the endpoint detectionmodule 1200. Some initial comments are warranted on the module 1200.Initially, the endpoint detection module 1200 may be used to identifythe endpoint of a plasma process having only a single endpoint.Multi-step plasma processes having corresponding multiple endpoints mayalso be evaluated through the endpoint detection module 1200. Two ormore plasma steps of a multiple step plasma process may each have theirrespective endpoints identified through the endpoint detection module1200. All steps of a multiple step plasma process having endpoints alsomay each be identified through the endpoint detection module 1200 aswell.

Multiple techniques may be simultaneously employed by the endpointdetection module 1200 to identify the occurrence of the endpoint(s) of aplasma process or portion thereof. One way in which this may beimplemented is to utilize two or more different endpoint detectiontechniques and to call endpoint when any one of these techniquesidentifies the subject endpoint. Different in this context means thatthe techniques themselves are different, and not merely the data whichis used by the technique. Another way in which this may be implementedis to utilize two or more endpoint detection techniques and to callendpoint when at least two of these techniques have identified thesubject endpoint. This option provides a more "robust" endpoint detectorby increasing the confidence that endpoint has actually beenappropriately identified (e.g., statistically more confident thatendpoint occurred).

The endpoint detection module 1200 may interface with the process alertmodule 428 of FIG. 14. For instance, when endpoint is identified throughthe endpoint detection module 1200, information on the endpointcondition may be provided to the appropriate personnel through the"alert" function of the process alert subroutine 432 of FIG. 14. Controlof the plasma process in relation to the identification of endpointthrough the endpoint detection module 1200 may also be affected throughthe "process control" function of the process alert subroutine 432. Theidentification of endpoint through the module 1200 may be used toterminate the current plasma process or discrete portion thereof (e.g.,a plasma step), to initiate the next aspect of the current plasmaprocess (e.g., the next plasma step), or both through the process alertsubroutine 432 and in the above-described manner.

Preferably, the current plasma process is evaluated both in relation toits health (i.e., the plasma health in accordance with the plasma healthmodule 252 discussed above) and in relation to endpoint through theendpoint detection module 1200. Although it is beneficial to monitor thehealth of the plasma process throughout substantially the entiretythereof (except possibly the initial portion thereof when the plasmafirst comes on and when the plasma is rather unstable), the endpointdetection module 1200 need not be initiated at the start of the plasmaprocess. Instead, the endpoint module 1200 preferably begins itsevaluation of the current plasma process to identify its endpoint(s) atan intermediate time in the process (e.g., at least 1/2 way into thesubject process or portion thereof). However, there is nothinginherently wrong with having the module 1200 evaluate the entirety ofthe plasma process to identify one or more of its endpoints. It justunnecessarily "consumes" processing time/capabilities. Moreover, theplasma health evaluation and endpoint evaluation need not be executed atthe same frequency or Analytical Time Resolution. The amount of timebetween which the health of the plasma process is checked may be greaterthan the time between which the plasma process is checked to identifyendpoint. For instance, the optical emissions of the plasma may bechecked at least at every 1 second for a plasma health evaluation, andmay be checked at least at every 300 milliseconds to identify endpoint.

Another feature may be included in each of the endpoint detectionsubroutines to be addressed below which also relates to plasma healthevaluations by the plasma health module 252. If the plasma health module252 identifies either an error or unknown condition in relation to thecurrent plasma process, this may have an effect on the operation of theendpoint detection module 1200. For instance, the endpoint detectionmodule 1200 may be configured to respond to such a condition bydisplaying information to the appropriate personnel that endpoint willnot be called because of the identification of the error or unknowncondition by the plasma health module 252. Moreover, if the endpointdetection module 1200 is interfaced with the controls of the processingchamber 36, identification of an error or unknown condition through theplasma health module 252 may terminate the ability of the endpointdetection module 1200 to affect any changes in the plasma process, toterminate a current plasma process after identifying its endpoint, toinitiate the next plasma process, or both. That is, the endpointdetection module 1200 may be "shut off" or disabled if the plasma healthis found to be unacceptable by the plasma health module 252 sinceendpoint information obtained under these circumstances may beunreliable.

One or more of the above-noted types of features may be incorporated ineach of the endpoint detection subroutines to be addressed below. Theremainder of the discussion presented herein on endpoint detectionthrough the endpoint detection module 1200 will only be in relation to aplasma step of a plasma recipe. However, it is equally applicable toendpoint detection for any type of plasma-related process.

One embodiment of an endpoint detection subroutine which may be calledby the endpoint module 1200 of FIGS. 7 and 32 is presented in FIG. 52.The endpoint detection subroutine 1456 is used to determine when a givenplasma step of a plasma recipe has affected its intended purpose orachieved the desired result. A current spectra of the plasma in theprocessing chamber 36 at the current time t_(c) is obtained for thesubroutine 1456 through execution of step 1460. An assessment of thisspectra from the processing chamber 36 with the endpoint subdirectory316 is undertaken at step 1464 to determine if endpoint has beenreached. One technique contemplated by step 1464 is to determine if thisspectra from the processing chamber 36, or at least a portion thereof,is a "match" with at least one spectra in the endpoint subdirectory 316of FIG. 9. Optical emissions data over a wavelength range (e.g., thePreferred Optical Bandwidth using the Preferred Data Resolution) may bestored in the endpoint subdirectory 316, such as a spectra obtained fromthe same processing chamber 36 during a previous execution of the sameplasma step at a time when endpoint should have been reached. Thepattern of the spectra of the plasma in the processing chamber 36 willtypically remain substantially constant for a time after endpoint hasbeen reached. Analyzing the data from a previous execution of thisplasma step in the same processing chamber 36 may therefore allow foridentification of a plurality of spectra at about the time whichendpoint should occur and which are undergoing no real significantchange. These spectra may be defined by the Preferred Optical Bandwidthand Preferred Data Resolution. One or more of these "steady state"spectra may then be included in the endpoint subdirectory 316 forcomparison with the current spectra for purposes of identifying a"match" in step 1468 of the endpoint detection subroutine 1456.Utilization may be made of the pattern recognition module 370 of FIG. 13by step 1464 and 1468 to see if there is a "match."

There are other ways of identifying a "match" indicative of endpoint instep 1468 of the endpoint detection subroutine 1456 of FIG. 52. One ormore wavelengths which were identified by the research module 1300 ofFIG. 49 may have their respective plots of intensity versus time from aprevious execution of the same plasma step in the same processingchamber 36 defined by an equation or function. In this case, theassessment through step 1464 may be to plot the optical emissions dataof this wavelength in the subsequent execution of the same plasmaprocess in the same chamber 36 and to determine if this data indeed fitswith this equation or function. If so, endpoint may be called when thecurrent optical data no longer "fits" the equation or function (e.g.,employing linear fit techniques, polynomial fit technique, etc) whichshould be at about the time where the "change" discussed above inrelation to the research module 1300 occurred. Other techniques whichmay be used to assess this type of current data would be to utilize afirst derivative or a second derivative of this equation or function todefine a linear function, such that deviations from this function may bemore readily identified in some cases as noted above (i.e., when theplot of the change in slope over time of the current optical datadeviates from the slope defined by the first or second derivative).

Features may be incorporated in the present invention to enhance theability to call endpoint based upon the behavior of one or more specificwavelengths. When the wavelengths which are indicative of endpoint areidentified through the research module 1300 of FIG. 49, certainrelational characteristics of these particular wavelengths may be notedas well. Consider the case where only a single wavelength has beenselected as an endpoint indicator. The intensity of the peak of thiswavelength may be noted to identify the same in any subsequentexecutions of the same plasma process. For instance, the subjectwavelength may represent the largest peak within a certain wavelengthregion. Therefore, the subject wavelength may be found in thesesubsequent executions by looking for the largest peak in a certain areaof the spectrum. In addition, the "position" of the peak of the subjectwavelength may be identified in relation to one or more other peaks. Forinstance, the subject wavelength may be represented by a peak which islocated between two larger peaks in a certain wavelength region.Therefore, the subject wavelength may be found in the subsequentexecutions by looking for this pattern in the optical emissions of theplasma.

If the assessment of the spectra of the plasma in the processing chamber36 at the current time t_(c) indicates that endpoint has not yet beenreached, the endpoint detection subroutine 1456 proceeds from step 1468to steps 1476 and 1470 which may be executed in any order. Step 1476resets the "clock" of the subroutine 1456 by increasing the current timet_(c) by a factor of "n." The magnitude of "n" defines the AnalyticalTime Resolution. Step 1470 makes a determination as to whether thecurrent plasma process has been terminated. The same types of techniquesdiscussed above in relation to determining when the plasma is "on" inthe chamber 36 may be used in step 1470. So long as the current plasmaprocess has not been terminated, the subroutine 1456 returns to step1460 where another spectra is obtained for the subroutine 1456 at thisnew current time t_(c) for a repetition of the above-described analysis.If the plasma process has been terminated, the subroutine 1456 proceedsfrom step 1470 to step 1466 where control of the plasma monitoringoperations may be returned to, for instance, the start-up module 202 ofFIG. 15. If no endpoint has been detected by the time at which theplasma process is terminated, information may be provided to personnelthat endpoint was not detected and that there may have been some erroror aberration in the process, even though the plasma health module 252did not necessarily identify this condition.

The endpoint detection subroutine 1456 of FIG. 52 will continue toexecute in the above-noted manner until step 1468 identifies endpointthrough steps 1464 and 1468. At this time the subroutine 1456 willproceed from step 1468 to step 1474 where the process alert module 428of FIG. 14 is called. There, actions may be taken to apprise personnelthat the endpoint of the subject plasma step has been reached (throughexecution of steps 454 and 458 of the process alert subroutine 432),actions may be taken in relation to control of the plasma process (e.g.,initiating the next plasma step or terminating the plasma recipe if thesubject step is the last step of the recipe), or both. Whether throughthe process alert module 428 or through step 1472 of the endpointdetection subroutine 1456, control of plasma monitoring operations maythen be returned to, for instance, the startup module 202 of FIG. 15.

Another embodiment of an endpoint detection subroutine which may beaccessed through the endpoint module 1200 is presented in FIG. 53. Theendpoint detection subroutine 1506 of FIG. 53 initiates at step 1510where a spectra of the plasma in the processing chamber 36 at thecurrent time t_(c) is obtained for the subroutine 1506. This spectra anda "reference" spectra are subtracted from each other at step 1514. Onlythe differential is important in relation to step 1514. That is, it isnot of particular importance whether the current spectra is subtractedfrom the "reference" spectra or vice versa. Preferably, both thereference spectra and the spectra on the current plasma process which isobtained are defined by the Preferred Optical Bandwidth and PreferredData Resolution.

At least two alternatives may be implemented for the "reference" spectrafrom step 1514 of the endpoint detection subroutine 1506. The"reference" spectra for step 1514 may be retrieved from the endpointsubdirectory 316 of FIG. 9. Preferably, the spectra from the endpointsubdirectory 316 which is the "reference" spectra for step 1514 of theendpoint detection subroutine 1506 is a spectra which is associated withthe same plasma process. That is, the spectra in the endpointsubdirectory 316 which is involved in the "subtraction" of step 1514would be a spectra from a previous execution of the same plasma processin the same processing chamber 36 at a time in the plasma process whenendpoint is at least assumed to have occurred. How this spectra isselected for inclusion in the endpoint subdirectory 316 may be inaccordance with the discussion presented above. Moreover, informationprovided by the operator, by direct communications between the waferproduction system 2 and the current plasma process module 250, or by thepattern recognition module 370 in which identifies the recipe, recipestep, etc, are detected, on the plasma process to be run in theprocessing chamber 36 may be used to select this spectra from theendpoint subdirectory 316 for use in the "subtraction" associated withstep 1514. Another option for the "reference" spectra for purposes ofstep 1514 is a previous-in-time spectra from the same plasma process inwhich the current spectra is obtained at step 1510 (e.g., theimmediately preceding current time t_(c)). For instance, the spectra atthe current time t_(c) and the spectra at the current time t_(c-n) maybe subtracted from each other at step 1514.

The subtraction operation involving the current spectra of the plasma inthe processing chamber 36 at the current time t_(c) and the "reference"spectra through execution of step 1514 of the endpoint detectionsubroutine 1514 generates an output which is indicative of thedifferential. If the subroutine 1506 determines that this differentialis within a certain predetermined tolerance at step 1518, endpoint willbe deemed to have been reached and the subroutine will proceed from step1518 to step 1530 where control is transferred to the process alertmodule 428 for action in accordance with the foregoing. Otherwise, thesubroutine 1506 will proceed from step 1518 to execute steps 1522 and1524. The order in which steps 1522 and 1524 are executed is of noparticular relevance. Step 1522 resets the "clock" of the subroutine1506 by increasing the current time t_(c) by a factor of "n." Themagnitude of "n" defines the Analytical Time Resolution. Step 1524 makesa determination as to whether the current plasma process has beenterminated. The same types of techniques discussed above in relation todetermining when the plasma is "on" in the chamber 36 may be used instep 1524. So long as the current plasma process has not beenterminated, the subroutine 1506 returns to step 1510 where anotherspectra is obtained for the subroutine 1506 at this new current timet_(c) for a repetition of the above-described analysis. If the plasmaprocess has been terminated, the subroutine 1506 proceeds from step 1524to step 1528 where control of the plasma monitoring operations may bereturned to, for instance, the start-up module 202 of FIG. 15.

The "differential" referred to in step 1518 of the endpoint detectionsubroutine 1506 of FIG. 53 may be compared with a predeterminedtolerance, such as baseline intensity. A raw difference basis, apercentage difference basis, or both may be used for establishing thistolerance. For example, when all of the data points involved in the"subtraction" of step 1514 are within ±"x" intensity units of eachother, the subroutine 1506 may be directed to proceed from step 1518 tostep 1530. Another way of saying this is that endpoint is deemed to havebeen reached for purposes of the endpoint detection subroutine 1506 whenthere are no longer any substantial peaks in the differential defined bystep 1514. These types of concepts are illustrated by reference to FIGS.54A-C, 55A-C, and 56A-C.

The spectra 1496a of FIG. 54A is representative of plasma in theprocessing chamber 36 in the initial part (e.g., for a current time t₀ )of a plasma step being run on product within the processing chamber 36(e.g., the spectra of FIG. 54A is the spectra at the current time t_(c)from step 1510 of the endpoint detection subroutine 1506 of FIG. 53).Spectra 1496a has a plurality of intensity peaks 1498a at variouswavelengths and at various intensities. The spectra 1500 of FIG. 54B isthe "reference" spectra from step 1514 of the endpoint detectionsubroutine 1506 and is defined by a plurality of peaks 1502 at variouswavelengths and with various intensities. FIG. 54C is an illustration ofthe "difference" between the spectra 1496a of FIG. 54A and the spectra1500 of FIG. 54C which is presented in the nature of an output 1504a.Note that the output 1504a in FIG. 54C has substantial peaks thereinwhich is indicative that endpoint has not yet been reached based uponthe logic of the endpoint detection subroutine 1506 of FIG. 53.

The spectra 1496b of FIG. 55A is representative of plasma in theprocessing chamber 36 at an intermediate time (e.g., for a current timet₃₀) in the same plasma step presented in FIG. 54A (i.e., the spectra ofFIG. 55A is the spectra at the current time t_(c) from step 1510 of theendpoint detection subroutine 1506 of FIG. 53). The spectra 1500 of FIG.55B is again the "reference" spectra from step 1514 of the endpointdetection subroutine 1506, and FIG. 55C is an illustration of the"difference" between the spectra 1496b of FIG. 55A and the spectra 1500of FIG. 55B which is presented in the nature of an output 1504b. Notethat the output 1504b in FIG. 55C still has substantial peaks thereinwhich is indicative that endpoint has not yet been reached based uponthe logic of the endpoint detection subroutine 1506. However, note thatthe plasma step has progressed in that the size of the peaks in theoutput 1504b of FIG. 55C is less than the size of the peaks from theoutput 1504a of FIG. 54C.

The spectra 1496c of FIG. 56A is representative of plasma in theprocessing chamber 36 toward the end (e.g., for a current time t₄₅) inthe same plasma step presented in FIGS. 54A and 55A (i.e., the spectraof FIG. 56A is the spectra at the current time t_(c) from step 1510 ofthe endpoint detection subroutine 1506 of FIG. 53). The spectra 1500 ofFIG. 56B is again the "reference" spectra from step 1514 of the endpointdetection subroutine 1506, and FIG. 56C is an illustration of the"difference" between the spectra 1496c of FIG. 56A and the spectra 1500of FIG. 56B which is presented in the nature of an output 1504c. Notethat the output 1504c in FIG. 56C now has no substantial peaks thereinwhich is indicative that endpoint has been reached based upon the logicof the endpoint detection subroutine 1506. Therefore, endpoint would becalled by the subroutine 1506 when the spectra of FIG. 56A isencountered for action in accordance with the foregoing.

Another embodiment of a subroutine which may be utilized by the endpointdetection module 1200 of FIGS. 7 and 32 is presented in FIG. 57.Generally, the endpoint detection subroutine 1204 of FIG. 57 associatesthe endpoint of a given plasma process or a discrete portion thereof(e.g., a plasma step) with a "modal" change in the plasma within thechamber 36 or a portion thereof around the time when endpoint hasoccurred. In many cases there is a change in impedance associated withthe processing chamber 36 at the time that endpoint is reached. Thischange in impedance oftentimes is reflected by a "modal" change in theplasma within the processing chamber 36 or a portion thereof. Changes inthe plasma are in turn reflected in its optical emissions. Endpointcould be called based upon this modal change alone (i.e., solely throughthe endpoint detection subroutine 1204 of FIG. 57). However, preferablythis "modal" change for identifying endpoint is used in combination withanother endpoint identification technique (e.g., through the endpointdetection subroutine 1456 of FIG. 52, through the endpoint detectionsubroutine 1506 of FIG. 53).

Optical emissions data are obtained for the endpoint detectionsubroutine 1204 of FIG. 57 at its step 1208. These optical emissionsdata are more specifically of the plasma in the processing chamber 36 ata time t_(c1). Two other time-related variables are introduced at step1212. A time t_(c1+n) is set equal to a time t_(c2) at step 1212. Assuch, the time t_(c2) is greater than the time t_(c1) by an increment of"n." The magnitude of "n" for the subroutine defines the Analytical TimeResolution. Optical emissions of the plasma in the processing chamber 36are obtained for this time t_(c2) through execution of step 1216 of theendpoint detection subroutine 1204.

The intensities of the optical emissions from the current values for thetimes t_(c1) and t_(c2) are compared with each other at step 1220 of theendpoint detection subroutine 1204. If the differential between theoptical emissions at these two times is less than a predetermined amount(e.g., an increase or a decrease of a certain magnitude), determinedthrough execution of step 1224, the subroutine 1204 proceeds from step1224 to step 1228. The time t_(c2) is set equal to the time t_(c1) atstep 1228 and spectral data for a new time t_(c2) is obtained by theendpoint detection subroutine 1204 returning to step 1212 for repetitionin accordance with the foregoing. In order to allow the subroutine 1204to exit the foregoing if the plasma process is terminated, a step 1240is incorporated which will provide this function by proceeding to a step1244 where control may be returned to, for instance, the start-up module202 of FIG. 15. Control may also be returned to the start-up module 202after endpoint is called in accordance with the following and throughexecution of step 1236.

If the differential between the optical emissions associated with thetimes t_(c1) and t_(c2) is ever more than the predetermined amountassociated with step 1224 of the endpoint detection subroutine 1204,this may be an indication of the above-noted "modal" change in theplasma which is in turn indicative of endpoint. It is not definitivelyindicative of the type of "modal" change at this point in time however.Only those "modal" changes associated with the plasma which occur atabout the time that endpoint is estimated to occur, which appear quicklyor abruptly, and which are persistently observed in subsequentexecutions of the same plasma process are indicative of a change inimpedance which occurs at endpoint. Therefore, it may be desirable toexecute a plurality of runs for each particular plasma process in whichthe subroutine 1204 is used before relying upon the subroutine 1204 tocall endpoint by execution of the process alert module 428 throughexecution of step 1232. The subroutine 1204 may also be implemented toconfirm or increase the confidence level that endpoint has been reachedwhen another endpoint detection technique is being used to call endpointas well.

The "modal" change associated with the endpoint detection subroutine1204 of FIG. 57 may be monitored in relation to one or more specificwavelengths, but by definition impacts plasma performance and isdetectable throughout the optical emissions range (although somewavelengths may demonstrate a stronger effect of the modal change thanothers). For instance, the optical emissions associated with thedifferential referred to in step 1224 may be in relation to a singlewavelength. Moreover, the optical emissions associated with thedifferential referred to in step 1224 may be from a plurality ofwavelengths, and the "differential" which is potentially indicative of achange in impedance may be when one or more of these wavelengthsdemonstrates the above-noted "modal" change. Another option is tomonitor for the "modal" change over a certain bandwidth. In this regard,the output 1260 presented in FIG. 58 illustrates the change in intensityof the plasma in the chamber 36 over time throughout the plasma step.More specifically, each point of the output 1260 illustrates thedifferential between the optical emissions of the plasma in the chamber36 over the Preferred Optical Bandwidth and at the Preferred DataResolution of a current time (e.g., t_(c)) and a preceding time (e.g.,t_(c-n)) Preferably, each data point which defines the output 1260 isthe differential between two adjacent times where optical emissions datais obtained from the chamber 36. As can be seen in the output 1260 fromFIG. 58, there is a significant change in the intensity of the plasmafrom about the 35 second mark and the 40 second mark. This is the typeof "modal" change which may be associated with a change in impedanceassociated with the processing chamber 36, which in turn the endpointdetection subroutine 1204 of FIG. 57 associates with endpoint.

Wafer Distribution Module 1384--FIGS. 59-60

Various of the above-noted evaluations provided by the current plasmaprocess module 250 may provide information to the wafer distributionmodule 1384 of FIGS. 59-60 to have some type of effect on thedistribution of wafers to the various process chambers 36 of the waferproduction system 2. One embodiment of a subroutine which may be used bythe wafer distribution module 1384 is illustrated in FIG. 59. Thesubroutine 1388 of FIG. 55 includes steps 1392, 1396, 1400, and 1402 inwhich the protocol is for the wafer distribution subroutine 1388 toproceed to the plasma process product module 252 for each of chambers36a-d (FIG. 1). The subroutine 1388 may of course accommodate waferproduction systems having different numbers of processing chambers 36.Monitoring of the current plasma recipes being run on product in each ofthese processing chambers 38a -d is included in the protocol of 1404.Any deviation from the normal spectra subdirectory 288 of the currentplasma recipe being run on product in any of the chambers 36a-d is notedat step 1408. In the case where the current plasma recipe being run onproduct in a given processing chamber 36 does not "match" any plasmarecipe within the normal spectra subdirectory 288, the distribution ofwafers 18 to this chamber 36 is suspended. This may be due to an errorin the subject plasma recipe identified by the plasma process productmodule 252 of FIGS. 21-25, the identification of an unknown condition inthe subject plasma recipe by the plasma process product module 252 ofFIGS. 21-25, or the identification of a dirty chamber condition by thechamber condition module 1084 of any of FIGS. 27-29. Although suspensionmay be implemented on the first occurrence of this type of event, thewafer distribution subroutine 1388 may be structured such that there isno suspension until a predetermined number of consecutive plasma recipeshave deviated from the normal spectra subdirectory 288 on a givenchamber 36 or when a certain percentage of a fixed number of plasmarecipes have deviated from the normal spectra subdirectory 288 on agiven chamber 36 (e.g., when at least one out of three runs have notmatched any plasma recipe in the normal spectra subdirectory 288).

Another embodiment of a subroutine which may be used by the waferdistribution module 1384 of FIGS. 7 and 32 is illustrated in FIG. 60.The subroutine 1416 includes steps 1420, 1424, 1428, and 1430 in whichthe protocol is for the wafer distribution subroutine 1416 to proceed tothe plasma process product module 252 for each of the respectiveprocessing chambers 36a-d (FIG. 1). The subroutine 1416 may of courseaccommodate wafer production systems having different numbers ofprocessing chambers 74. Monitoring of the current plasma recipes beingrun on product in each of these processing chambers 36a-d is included inthe protocol of step 1432. The total time required to execute eachplasma recipe on each of the chambers 36 is also noted at step 1432.Step 1432 may thereby use the plasma process product module 252discussed above in relation to FIGS. 21-25, as well as the endpointmodule 1200 discussed above in relation to FIGS. 52-58. The distributionsequence of wafers 18 to these chambers 36 is based upon the total timerequired to complete each plasma recipe as noted in step 1436.

The logic of step 1436 of the wafer distribution subroutine 1416 may bethat a priority is given to the processing chamber 36 which is executingthe plasma recipe in the shortest amount of time. That is, thedistribution sequence of wafers 18 to the chamber 36 may be to utilizethe "fastest" processing chamber 36 the most. If the "fastest" chamberwas 36a and is available (i.e., no product therein), the logic of step1436 would instruct the wafer handling assembly 44 to provide a wafer 18to this chamber 36a even though another chamber (e.g., chamber 36b ) is"scheduled" to receive the next wafer 18. Alternatively, the logic ofstep 1436 may be that a priority is given to the processing chamber 36which is executing the plasma recipe over the longest period of time.Lengthening of the time required to execute a plasma recipe may indicatethat the chamber 36 is becoming dirty, and may be in need of "cleaning"in the near future as discussed above in relation to the chambercondition module 1084 of FIGS. 27-29. Since this is the case, theoperator of the facility incorporating the wafer production system 2 maydecide to maximize the runs on a given chamber 36 once it has beendetermined that it will be taken "off-line" in the near future forcleaning.

Conclusion

The plasma monitoring assemblies 174, 500, and 700 as described aboveoffers numerous advantages. One advantage is that the logic of thecurrent plasma process module 250 and its various sub-modules can beused with any type of plasma chamber and further can be used to evaluateany type of plasma process. No significant adaptation of the logic ofthe module 250 or any of its submodules is required to use the module250 on one chamber type/design, and then to turn around and use thissame module 250 on another chamber type/design. Similarly, no adaptationof the module 250 or any of its sub-modules is required to use themodule 250 on one type of plasma process, and then to turn around anduse this same module 250 on a plasma process which is somehow different.In this sense the module 250 is a generic plasma monitoring tool.

Another advantage of the plasma monitoring assemblies 174, 500, 700 isthat the data which is used to evaluate the plasma processes conductedwithin a processing chamber is taken from this very same processingchamber when running the very same type of plasma process. In this sensewhen the assemblies 174, 500, and 700 are installed on a particularprocessing chamber, the assemblies 174, 500, 700 become specific to thechamber. The fact that a given plasma recipe will behave in one way onone chamber and another way on another chamber is of no significance tothe plasma monitoring assemblies 174, 500, 700. Each assembly 174, 500,700 adapts to the idiosyncrasies of its associated chamber and learnsabout the chamber through the running of actual plasma processes on thechamber to build up the plasma spectra directory 284 for that particularchamber. Again, each chamber will have its own plasma spectra directory284 or the like in that all information used to evaluation a givenplasma process on a given plasma chamber will have been obtained fromthis very same processing chamber.

Significant information on the current plasma process is made availablepursuant to the current plasma process product module 250 and itsvarious submodules. The module 250 has the ability to: determine if thecurrent plasma process is proceeding like one or more previous runningsof this same plasma process on this same chamber; determine if theendpoint of a given plasma step has been reached; determine if theendpoint of each plasma step in a plasma recipe has been reached;identify the current plasma recipe to operations personnel; identify thecurrent plasma step to operations personnel; determine when a chambershould be cleaned; and to determine when each of a plasma cleaning, andconditioning wafer operation may be terminated. How this information isused will typically be left up to the discretion of the operator of thefacility incorporating the wafer production system 2. For instance, thecurrent plasma process module 250 may simply be used a source ofinformation on the current plasma process. The current plasma processmodule 250 may also take a more active roll in the operation of thewafer production system 2 by integrating the module 250 with processcontrols for the system 2, such as to automate control of plasma processoperations based upon information provided by the module 250. Variouscombinations may also be employed in that any sub-module may be"programmed" to be for information only, for process control only, orfor both. Flexibility to deal with these types of issues is provided bythe modular construction of the current plasma process module 250 wherethe module 250 and each of its sub-modules are again preferably storedon a computer-readable data storage medium (e.g., computer-readablememory such as one or more hard disks, floppy disks, zip-drive disks,CDs). Therefore, changes to the structure of the current plasma processmodule 250 may be readily implemented.

The foregoing description of the present invention has been presentedfor purposes of illustration and description. Furthermore, thedescription is not intended to limit the invention to the form disclosedherein. Consequently, variations and modifications commensurate with theabove teachings, and skill and knowledge of the relevant art, are withinthe scope of the present invention. The embodiments describedhereinabove are further intended to explain best modes known ofpracticing the invention and to enable others skilled in the art toutilize the invention in such, or other embodiments and with variousmodifications required by the particular application(s) or use(s) of thepresent invention. It is intended that the appended claims be construedto include alternative embodiments to the extent permitted by the priorart.

What is claimed is:
 1. A plasma processing system, comprising:aprocessing chamber comprising a window, wherein said window comprises aninner surface which is exposed to a plasma process conducted within saidchamber and an outer surface which is isolated from said plasma process;a plasma generator in said processing chamber, wherein said plasmaprocess may be run in said processing chamber when said plasma generatoris activated; a first spectrometer assembly disposed outside of saidprocessing chamber; a first fiber optic cable assembly operativelyinterconnecting said first spectrometer assembly and said window; acalibration light source disposed outside of said processing chamber andcomprising a calibration light; a second fiber optic cable assemblyoperatively interconnecting said calibration light source and saidwindow; and a comparator operatively interconnected with said firstspectrometer assembly, wherein a first input to said comparator is datarelating said calibration light sent to said window by said calibrationlight source through said second fiber optic cable assembly and whereina second input to said comparator is data relating to a first portion ofsaid calibration light reflected by said inner surface of said windowand provided to said first spectrometer assembly through said firstfiber optic cable assembly.
 2. A system, as claimed in claim 1,wherein:said first spectrometer assembly is selected from the groupconsisting of at least one scanning-type spectrometer and at least onesolid state spectrometer.
 3. A system, as claimed in claim 1,wherein:said first spectrometer assembly comprises a plurality ofspectrometers, wherein each said spectrometer covers a differentwavelength region.
 4. A system, as claimed in claim 1, wherein:saidwindow comprises a first location and a second location which is spacedfrom said first location, wherein a thickness of said window variesprogressing from said first location to said second location to limitthat portion of said calibration light, which is reflected by saidwindow and collected by said first fiber optic cable assembly for use bysaid first spectrometer assembly and said comparator, to said firstportion of said calibration light.
 5. A system, as claimed in claim 1,wherein:a first end of each of said first and second fiber optic cableassemblies are coaxially disposed, wherein said inner surface of saidwindow is disposed at least substantially perpendicular to an axis oflight leaving and entering said first end of said second and first fiberoptic cable assemblies, respectively, and wherein said outer surface ofsaid window is disposed at an angle other than perpendicular relative tosaid axis of light leaving and entering said first end of said secondand first fiber optic cable assemblies, respectively, both of whichlimits that portion of said calibration light, which is reflected bysaid window and collected by said first fiber optic cable assembly foruse by said first spectrometer assembly and said comparator, to saidfirst portion of said calibration light.
 6. A system, as claimed inclaim 1, wherein:said inner and outer surfaces of said window aredisposed other than in parallel relation to limit that portion of saidcalibration light, which is reflected by said window and collected bysaid first fiber optic cable assembly for use by said first spectrometerassembly and said comparator, to said first portion of said calibrationlight.
 7. A system, as claimed in claim 1, wherein:said window is atleast generally wedge-shaped.
 8. A system, as claimed in claim 1,wherein:a first end of said second fiber optic cable assembly directedtoward said window is coaxially disposed with a first end of said firstfiber optic cable assembly directed toward said window to receive saidfirst portion of said calibration light reflected by said inner surfaceof said window.
 9. A system, as claimed in claim 8, wherein:said innerand outer surfaces of said window are disposed other than in parallelrelation, and wherein said system further comprises:means formaintaining said first end of each of said first and second fiber opticcable assemblies in a fixed positional relationship relative to saidwindow whereby:said calibration light from said calibration light sourcedirected through said second fiber optic cable assembly impacts saidouter surface of said window at an angle other than perpendicularrelative to said outer surface to direct at least substantially allportions of said calibration light reflected by said outer surface ofsaid window away from said first fiber optic cable assembly, and furtherwhereby a portion of said calibration light from said calibration lightsource which impacts said inner surface of said window does so at leastsubstantially perpendicular to said inner surface of said window todirect said first portion of said calibration light reflected by saidinner surface of said window into said first fiber optic cable assemblyfor provision to said first spectrometer assembly for use by saidcomparator.
 10. A system, as claimed in claim 1, wherein:an axis oflight leaving said second fiber optic cable assembly impacts said innersurface of said window at a first acute angle relative to said innersurface, and wherein an end of said first fiber optic cable assembly isdisposed so as to collect said first portion of said calibration lightreflected by said inner surface, whereby an end of said second fiberoptic cable assembly which directs said calibration light toward saidwindow is disposed on an opposite side of a reference plane whichintersects said window than said end of said first fiber optic cableassembly which receives said first portion of said calibration lightreflected by said window.
 11. A system, as claimed in claim 1,wherein:said comparator comprises means for comparing a pattern of saidcalibration light sent to said window with a pattern of said firstportion of said calibration light reflected by said inner surface ofsaid window.
 12. A system, as claimed in claim 1, further comprising:aplasma monitoring assembly operatively interconnected with said windowand comprising said first spectrometer assembly; and means for making atleast one adjustment in relation to said plasma monitoring assemblybased upon an output from said comparator.
 13. A system, as claimed inclaim 1, wherein:at least a portion of said outer surface of said windowcomprises an anti-reflective coating aligned with said second fiberoptic cable assembly.
 14. A system, as claimed in claim 1, wherein:saidcalibration light source comprises a first calibration light source anda second calibration light source, said first calibration light sourcebeing of a different type of light than said second calibration lightsource.
 15. A system, as claimed in claim 14, wherein:said firstcalibration light source comprises a first calibration light comprisinga plurality of discrete intensity peaks and wherein said secondcalibration light source comprises a second calibration light comprisinga continuum of intensity.
 16. A system, as claimed in claim 14,wherein:said first calibration light source is used to identify awavelength shift and said second calibration light source is used toidentify an intensity shift.
 17. A system, as claimed in claim 1,further comprising:a fiber optic cable fixture assembly, wherein saidfixture assembly comprises a recessed region which interfaces with atleast a portion of said outer surface of said window and a first portwhich extends through said fixture assembly to intersect with saidrecessed region, wherein at least a portion of said fixture assemblywhich defines said recessed region comprises a light absorbing material,wherein first ends of said first and second fiber optic cable assembliesare attached to said fixture assembly in axial alignment with said firstport, and wherein a reference axis projecting from said first ends ofsaid first and second fiber optic cable assemblies toward said windoweach intersect said outer surface of said window at an angle other thanperpendicular and each intersect said inner surface of said window atleast at a substantially perpendicular angle.
 18. A system, as claimedin claim 17, wherein:said first ends of said first and second fiberoptic cable assemblies are coaxially disposed and threadablyinterconnected with said fixture assembly.
 19. A plasma processingsystem, comprising:a processing chamber comprising a window, whereinsaid window comprises an inner surface which is exposed to a plasmaprocess conducted within said chamber and an outer surface which isisolated from said plasma process; a plasma generator in said processingchamber, wherein said plasma process may be run in said processingchamber when said plasma generator is activated; a first spectrometerassembly disposed outside of said processing chamber; a first fiberoptic cable assembly operatively interconnecting said first spectrometerassembly and said window; a calibration light source disposed outside ofsaid processing chamber and comprising a calibration light; and a secondfiber optic cable operatively interconnecting said calibration lightsource and said window, wherein said inner and outer surfaces of saidwindow on said processing chamber are disposed other than in parallelrelation to reduce interference between portions of said calibrationlight reflected by said inner and outer surfaces, respectively.
 20. Asystem, as claimed in claim 19, wherein:said first spectrometer assemblyis selected from the group consisting of at least one scanning-typespectrometer and at least one solid state spectrometer.
 21. A system, asclaimed in claim 19, wherein:said first spectrometer assembly comprisesa plurality of spectrometers, wherein each said spectrometer covers adifferent wavelength region.
 22. A system, as claimed in claim 19,wherein:said window comprises a first location and a second locationwhich is spaced from said first location, wherein a thickness of saidwindow varies progressing from said first location to said secondlocation to limit that portion of said calibration light, which isreflected by said window and collected by said first fiber optic cableassembly for use by said first spectrometer assembly, to a portion ofsaid calibration light which is reflected by said inner surface of saidwindow.
 23. A system, as claimed in claim 19, wherein:a first end ofeach of said first and second fiber optic cable assemblies are coaxiallydisposed, wherein said inner surface of said window is disposed at leastsubstantially perpendicular to an axis of light leaving and enteringsaid first end of said second and first fiber optic cable assemblies,respectively, and wherein said outer surface of said window is disposedat an angle other than perpendicular relative to said axis of lightleaving and entering said first end of said second and first fiber opticcable assemblies, respectively, both of which limits that portion ofsaid calibration light, which is reflected by said window and collectedby said first fiber optic cable assembly for use by said firstspectrometer assembly, to a portion of said calibration light reflectedby said inner surface of said window.
 24. A system, as claimed in claim19, wherein:said window is at least generally wedge-shaped.
 25. Asystem, as claimed in claim 19, wherein:a first end of said second fiberoptic cable assembly directed toward said window is coaxially disposedwith a first end of said first fiber optic cable assembly directedtoward said window to receive a portion of said calibration lightreflected by said inner surface of said window.
 26. A system, as claimedin claim 25, further comprising:means for maintaining said first end ofeach of said first and second fiber optic cable assemblies in a fixedpositional relationship relative to said window whereby:said calibrationlight from said calibration light source directed through said secondfiber optic cable assembly impacts said outer surface of said window atan angle other than perpendicular relative to said outer surface todirect at least substantially all portions of said calibration lightreflected by said outer surface of said window away from said firstfiber optic cable assembly, and further whereby a portion of saidcalibration light from said calibration light source which impacts saidinner surface of said window does so at least substantiallyperpendicular to said inner surface of said window to direct at least aportion of said calibration light reflected by said inner surface ofsaid window into said first fiber optic cable assembly for provision tosaid first spectrometer assembly.
 27. A system, as claimed in claim 19,wherein:an axis of light leaving said second fiber optic cable assemblyimpacts said inner surface of said window at a first acute anglerelative to said inner surface, and wherein an end of said first fiberoptic cable assembly is disposed so as to collect at least a portion ofsaid calibration light reflected by said inner surface, whereby an endof said second fiber optic cable assembly which directs said calibrationlight toward said window is disposed on an opposite side of a referenceplane which intersects said window than said end of said first fiberoptic cable assembly which receives said at least a portion of saidcalibration light reflected by said inner surface of said window.
 28. Asystem, as claimed in claim 19, further comprising:a comparatoroperatively interconnected with said first spectrometer assembly,wherein a first input to said comparator is data relating saidcalibration light sent to said window by said calibration light sourcethrough said second fiber optic cable assembly and wherein a secondinput to said comparator is data relating to a first portion of saidcalibration light reflected by said inner surface of said window andprovided to said first spectrometer assembly through said first fiberoptic cable assembly.
 29. A system, as claimed in claim 28, wherein:saidcomparator comprises means for comparing a pattern of said calibrationlight sent to said window with a pattern of said first portion of saidcalibration light reflected by said inner surface of said window.
 30. Asystem, as claimed in claim 28, further comprising:a plasma monitoringassembly operatively interconnected with said window and comprising saidfirst spectrometer assembly; and means for making at least oneadjustment in relation to said plasma monitoring assembly based upon anoutput from said comparator.
 31. A system, as claimed in claim 19,wherein:at least a portion of said outer surface of said windowcomprises an anti-reflective coating aligned with said second fiberoptic cable assembly through which said calibration light exits saidsecond fiber optic cable assembly.
 32. A system, as claimed in claim 19,wherein:said calibration light source comprises a first calibrationlight source and a second calibration light source, said firstcalibration light source being of a different type of light than saidsecond calibration light source.
 33. A system, as claimed in claim 32,wherein:said first calibration light source comprises a firstcalibration light comprising a plurality of discrete intensity peaks andwherein said second calibration light source comprises a secondcalibration light comprising a continuum of intensity.
 34. A system, asclaimed in claim 32, wherein:said first calibration light source is usedto identify a wavelength shift and said second calibration light sourceis used to identify an intensity shift.
 35. A system, as claimed inclaim 19, further comprising:a fiber optic cable fixture assembly,wherein said fixture assembly comprises a recessed region whichinterfaces with at least a portion of said outer surface of said windowand a first port which extends through said fixture assembly tointersect with said recessed region, wherein at least a portion of saidfixture assembly which defines said recessed region comprises a lightabsorbing material, wherein first ends of said first and second fiberoptic cable assemblies are attached to said fixture assembly in axialalignment with said first port, and wherein a reference axis projectingfrom said first ends of said first and second fiber optic cableassemblies toward said window each intersect said outer surface of saidwindow at an angle other than perpendicular and each intersect saidinner surface of said window at least at a substantially perpendicularangle.
 36. A system, as claimed in claim 35, wherein:said first ends ofsaid first and second fiber optic cable assemblies are coaxiallydisposed and threadably interconnected with said fixture assembly.
 37. Aplasma processing system, comprising:a processing chamber comprising awindow, wherein said window comprises an inner surface which is exposedto a plasma process conducted within said chamber and an outer surfacewhich is isolated from said plasma process; means for generating aplasma within said processing chamber to conduct said plasma processwithin said processing chamber; means for obtaining optical emissions ofsaid plasma within said chamber which are emitted through said windowduring said plasma process; means for evaluating said plasma processthrough output from said means for obtaining; and a calibration assemblyoperatively interconnected with said means for evaluating, wherein saidcalibration assembly comprises:means for directing a calibration lightto said window; means for comparing a portion of said calibration lightreflected by said window with said calibration light from said means fordirecting; and means for limiting said portion of said calibration lightused by said means for comparing to a portion of said calibration lightfrom said means for directing which is reflected by said inner surfaceof said window.
 38. A system, as claimed in claim 37, wherein:said meansfor obtaining comprises at least one spectrometer.
 39. A system, asclaimed in claim 37, wherein:said means for evaluating comprises meansfor comparing a pattern of said optical emissions from a current saidplasma process with a pattern of previous-in-time optical emissions fromat least one said plasma process.
 40. A system, as claimed in claim 37,wherein:said means for limiting comprises means for directing saidcalibration light to said window to impact said outer surface of saidwindow at an angle other than perpendicular relative to said outersurface to direct at least substantially all portions of saidcalibration light reflected by said outer surface of said window so asto be unavailable for use by said means for comparing, and such that aportion of said calibration light impacts said inner surface of saidwindow to direct at least a portion of said calibration light reflectedby said inner surface of said window so as to be available for use bysaid means for comparing.
 41. A system, as claimed in claim 37,wherein:said means for comparing comprises means for comparing a patternof said calibration light from said means for directing with a patternof said portion of said calibration light reflected by said window. 42.A system, as claimed in claim 37, wherein:said calibration assemblyfurther comprises means for calibrating said means for evaluating foreach of first and second conditions, said first condition being awavelength shift associated with said optical emissions which are usedby said means for evaluating, said second condition being an intensityshift associated with said optical emissions which are used by saidmeans for evaluating.
 43. A system, as claimed in claim 37, wherein:saidoptical emissions associated with said means for obtaining are within afirst wavelength range, and wherein said calibration assembly furthercomprises means for determining if said window is filtering out any saidoptical emissions which are within a first wavelength region which iscontained within said first wavelength range.
 44. A system, as claimedin claim 37, wherein:said optical emissions associated with said meansfor obtaining are within a first wavelength range, and wherein saidcalibration assembly further comprises means for determining if saidwindow is having a first dampening effect on a first wavelength regionwhich is within said first wavelength range, as well as a seconddampening effect on a second wavelength region which is both within saidfirst wavelength range and outside of said first wavelength region,wherein said first and second dampening effects are different.
 45. Asystem, as claimed in claim 37, wherein:said means for limitingcomprises an anti-reflective coating on at least a portion of said outersurface of said window.
 46. A system, as claimed in claim 37,wherein:said means for directing comprises means for directing first andsecond calibration lights to said window, said first calibration lightbeing of a different type of light than said second calibration light.47. A system, as claimed in claim 46, wherein:said first calibrationlight comprises a plurality of discrete intensity peaks and wherein saidsecond calibration light comprises a continuum of intensity.
 48. Asystem, as claimed in claim 47, wherein:said first calibration lightsource is used by said calibration assembly to identify a wavelengthshift associated with said means for evaluating and said secondcalibration light source is used by said calibration assembly toidentify an intensity shift associated with said means for evaluating.49. A system, as claimed in claim 37, wherein:said means for obtainingcomprises a first fiber optic cable assembly and said means forcalibration assembly comprises a second fiber optic cable assembly, saidsystem further comprising a fiber optic cable fixture assembly, whereinsaid fixture assembly comprises a recessed region which interfaces withat least a portion of said outer surface of said window and a first portwhich extends through said fixture assembly to intersect with saidrecessed region, wherein at least a portion of said fixture assemblywhich defines said recessed region comprises a light absorbing material,wherein first ends of said first and second fiber optic cable assembliesare attached to said fixture assembly in axial alignment with said firstport, and wherein said window is configured and said fixture assembly isdisposed relative to said window such that a reference axis projectingfrom said first ends of said first and second fiber optic cableassemblies toward said window each intersect said outer surface of saidwindow at an angle other than perpendicular and each intersect saidinner surface of said window at least at a substantially perpendicularangle.
 50. A system, as claimed in claim 49, wherein:said first ends ofsaid first and second fiber optic cable assemblies are coaxiallydisposed and threadably interconnected with said fixture assembly.